Propulsion system cooling control

ABSTRACT

A propulsion system includes an electric fan propulsion motor with a plurality of propulsion motor windings. The propulsion system also includes a means for controlling a flow rate of a working fluid through a cryogenic working fluid flow control assembly to the propulsion motor windings.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to U.S. ProvisionalApplication No. 62/647,055 filed Mar. 23, 2018, U.S. ProvisionalApplication No. 62/647,060 filed Mar. 23, 2018, U.S. ProvisionalApplication No. 62/653,599 filed Apr. 6, 2018, U.S. ProvisionalApplication No. 62/653,602 filed Apr. 6, 2018, U.S. ProvisionalApplication No. 62/653,604 filed Apr. 6, 2018, U.S. ProvisionalApplication No. 62/656,451 filed Apr. 12, 2018, and U.S. ProvisionalApplication No. 62/656,453 filed Apr. 12, 2018, the disclosures of whichare incorporated herein by reference in their entirety.

BACKGROUND

Exemplary embodiments pertain to aircraft systems, and more particularlyto systems and methods for propulsion system cooling control andcryogenic systems.

Gas turbine engines can provide propulsion and power on an aircraft.Aircraft can include separate systems that control propulsion, thermalmanagement, and other functions. Aircraft environmental control systemscan be used to remove heat from various aircraft lubrication andelectrical systems and/or used to condition aircraft cabin air. Aircycle packs of an aircraft environmental control system can conditionoutside (fresh) air for cabin heating and cooling. The air temperaturesand pressures from air cycle packs can be conditioned to match typicalindoor environments deemed comfortable for occupants.

Gas turbine engines can be implemented as Brayton cycle machines withbalanced thermodynamic cycles, where work is a function of pressure andvolume, and heat transfer is balanced. The net work for a thermodynamicexchange in a gas turbine engine may be expressed as work done on asubstance due to expansion minus work done on recompression. Work can belost at thermodynamic exchanges where a cooling air branch occurswithout imparting a motive force to turbomachinery within a gas turbineengine. In some instances, pressures and temperatures within a gasturbine engine are constrained due to material properties, which canresult in designs that are less efficient through losses than mayotherwise be needed.

Placement and use of gas turbine engines may be limited on or within anaircraft due to constraints on air intake, exhaust, fuel supply, andother factors. Electric propulsion motors can be effective at drivingrotating elements but may be limited in use for providing aircraftthrust due to constraints on power density, electric power demand,heating effects, and weight.

BRIEF DESCRIPTION

Disclosed is a system for an aircraft. The system includes an enginebleed source of a gas turbine engine. The system also includes a meansfor chilling an engine bleed air flow from the engine bleed source toproduce a chilled working fluid at a temperature below a boiling pointof oxygen and above a boiling point of nitrogen. The system furtherincludes a means for providing the chilled working fluid for an aircraftuse.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forchilling the engine bleed air flow is a cryogenic cooling systemincluding a compressor operable to further compress the engine bleed airflow as compressed air and at least one turbine operable to expand andcool the compressed air as the chilled working fluid.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the aircraftuse includes cooling one or more components of the aircraft.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the aircraftuse includes an increased airflow to one or more of: components of thegas turbine engine, a cabin of the aircraft, and electronics of theaircraft.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include a means forseparating gaseous nitrogen from the chilled working fluid as a gaseousnitrogen supply and separating liquid oxygen from the chilled workingfluid as a liquid oxygen supply.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forseparating gaseous nitrogen and liquid oxygen is an impact plate-basedseparator including an impact plate positioned proximate to an inputport to alter a flow direction of the chilled working fluid.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forseparating gaseous nitrogen and liquid oxygen is an impact plate-basedseparator comprising an impact plate positioned proximate to an inputport to alter a flow direction of the chilled working fluid.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forseparating gaseous nitrogen and liquid oxygen is a stagnationplate-based separator including a stagnation plate with variations incurvature and flow paths to alter a flow velocity and pressure of thechilled working fluid.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forseparating gaseous nitrogen and liquid oxygen is a magnetic-basedseparator including a magnetic field generator operable to produce amagnetic field to attract the liquid oxygen towards a liquid oxygenoutput port.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where at least aportion of the gaseous nitrogen supply is provided to one or more of: afuel system of the aircraft and a location downstream of a combustor ofthe gas turbine engine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where at least aportion of the liquid oxygen supply is provided to one or more of: acabin of the aircraft and a compressor stream of the gas turbine engine.

Also disclosed is a method that includes providing an engine bleed airflow from an engine bleed source of a gas turbine engine to a cryogeniccooling system. The engine bleed air flow is chilled using the cryogeniccooling system to produce a chilled working fluid at a temperature belowa boiling point of oxygen and above a boiling point of nitrogen. Thechilled working fluid is provided for an aircraft use.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include compressing theengine bleed air flow as compressed air by a compressor of the cryogeniccooling system, and expanding and cooling the compressed air as thechilled working fluid by at least one turbine of the cryogenic coolingsystem.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the aircraftuse includes cooling and increasing an airflow to one or more componentsof the aircraft.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include separating gaseousnitrogen from the chilled working fluid as a gaseous nitrogen supply,and separating liquid oxygen from the chilled working fluid as a liquidoxygen supply.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where separatinggaseous nitrogen and liquid oxygen is performed using an impactplate-based separator including an impact plate positioned proximate toan input port to alter a flow direction of the chilled working fluid.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where separatinggaseous nitrogen and liquid oxygen is performed using a stagnationplate-based separator including a stagnation plate with variations incurvature and flow paths to alter a flow velocity and pressure of thechilled working fluid.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where separatinggaseous nitrogen and liquid oxygen is performed using a magnetic-basedseparator including a magnetic field generator operable to produce amagnetic field to attract the liquid oxygen towards a liquid oxygenoutput port.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include providing at least aportion of the gaseous nitrogen supply to one or more of: a fuel systemof the aircraft and a location downstream of a combustor of the gasturbine engine, and providing at least a portion of the liquid oxygensupply to one or more of: a cabin of the aircraft and a compressorstream of the gas turbine engine.

Also disclosed is a system for an aircraft. The system includes a gasturbine engine operable to produce thrust for the aircraft, and a meansfor cryogenically cooling an engine bleed air flow of the gas turbineengine to produce a chilled working fluid at a temperature below aboiling point of oxygen and above a boiling point of nitrogen for anaircraft use.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forcryogenically cooling the engine bleed air flow includes a compressoroperable to further compress the engine bleed air flow as compressed airand at least one turbine operable to expand and cool the compressed airas the chilled working fluid.

Disclosed is a system for an aircraft. The system includes an enginebleed source of a gas turbine engine and a means for chilling an enginebleed air flow from the engine bleed source to produce liquid air. Thesystem further includes a means for providing the liquid air for anaircraft use.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forchilling the engine bleed air flow is a cryogenic cooling systemincluding a heat exchanger system operable to pre-cool the engine bleedair flow, a compressor operable to further compress the engine bleed airflow as compressed air, and at least one turbine operable to expand andcool the compressed air as a cooled flow.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the cryogeniccooling system further includes a vacuum system and a condensate pumpsystem operable to condense the liquid air from the cooled flow and urgethe liquid air through a feeder line.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the heatexchanger system is operable to receive a cooling air intake and furthercool the compressed air prior to reaching the at least one turbine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forproviding the liquid air for the aircraft use includes at least one pumpin fluid communication with the feeder line and a plumbing systemcomprising one or more lines and valves.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include a cryogenic airseparator operable to separate gaseous nitrogen from the liquid air as agaseous nitrogen supply and separate liquid oxygen from the liquid airas a liquid oxygen supply.

Also disclosed is a method that includes providing an engine bleed airflow from an engine bleed source of a gas turbine engine to a cryogeniccooling system. The method also includes chilling the engine bleed airflow using the cryogenic cooling system to produce liquid air andpumping the liquid air for an aircraft use.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include pre-cooling theengine bleed air flow using a heat exchanger system, and compressing theengine bleed air flow as compressed air by a compressor of the cryogeniccooling system. The method also includes expanding and cooling thecompressed air as a cooled flow by at least one turbine of the cryogeniccooling system.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include condensing the liquidair from the cooled flow and urging the liquid air through a feederline.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include receiving a coolingair intake at the heat exchanger system and further cooling thecompressed air prior to reaching the at least one turbine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where aircraft useincludes cooling and increasing an airflow to one or more components ofthe aircraft.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include separating gaseousnitrogen from the liquid air as a gaseous nitrogen supply, andseparating liquid oxygen from the liquid air as a liquid oxygen supply.

Also disclosed is a system for an aircraft. The system includes a gasturbine engine operable to produce thrust for the aircraft, and a meansfor cryogenically cooling the aircraft based on an engine bleed sourceof the gas turbine engine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forcryogenically cooling the aircraft is a cryogenic cooling systemincluding a heat exchanger system operable to pre-cool the engine bleedair flow, a compressor operable to further compress the engine bleed airflow as compressed air, and at least one turbine operable to expand andcool the compressed air as a cooled flow, a vacuum system, and acondensate pump system operable to condense liquid air from the cooledflow and urge the liquid air through a feeder line to cool one or morecomponents of the aircraft.

Disclosed is an engine-driven cryogenic cooling system for an aircraft.The engine-driven cryogenic cooling system includes a first air cyclemachine including a plurality of components operably coupled to agearbox of a gas turbine engine and configured to produce a cooling airstream based on a first engine bleed source of the gas turbine engine.The engine-driven cryogenic cooling system also includes a second aircycle machine operable to output a chilled air stream at a cryogenictemperature based on a second engine bleed source cooled by the coolingair stream of the first air cycle machine. The engine-driven cryogeniccooling system further includes a means for condensing the chilled airstream into liquid air for an aircraft use.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the componentsof the first air cycle machine include a first compressor section and afirst turbine section, and the second air cycle machine includes asecond compressor section and a second turbine section.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the firstcompressor section includes a first compressor wheel operably coupled tothe gearbox, the first turbine section includes one or more turbinewheels operably coupled to the gearbox, and the gearbox is operablycoupled to a tower shaft of the gas turbine engine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include an air-air heatexchanger interposed in fluid communication between the first enginebleed source and the first compressor wheel, and a fuel-air heatexchanger interposed in fluid communication between the air-air heatexchanger and a first turbine wheel of the first turbine section.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where an output ofthe first turbine wheel is selectively provided to a first cooling useof the aircraft, and a second turbine wheel in fluid communication withthe first turbine wheel is operable to output the cooling air streamthat is selectively provided to a second cooling use and the second aircycle machine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include a selection valveinterposed in fluid communication between the air-air heat exchanger andthe fuel-air heat exchanger, the selection valve is operable to directan output of the air-air heat exchanger to the first compressor wheel orthe fuel-air heat exchanger; and a mixing chamber in fluid communicationwith the first compressor wheel, a high pressure compressor of the gasturbine engine, and a turbine cooling air input between the highpressure compressor and a combustor of the gas turbine engine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include a heat exchangersystem operable to pre-cool an air flow from the second engine bleedsource prior to entry into the second compressor section of the secondair cycle machine and cool the air flow after exiting the secondcompressor section, and a cooling fan operably coupled to the secondcompressor section and configured to urge a heat exchanger cooling flowacross the heat exchanger system, the heat exchanger cooling flowincluding the cooling air stream of the first air cycle machine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the heatexchanger cooling flow provides a cooling source for the aircraft aftercrossing the heat exchanger system.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forcondensing the chilled air stream includes a vacuum system configured toreceive the chilled air stream and maintain one or more exit conditionsof the second turbine section, a liquid air condensate pump systemoperable to urge the liquid air through a feeder line, and a cryogenicliquid reservoir operably coupled to the feeder line for the aircraftuse.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include a vacuum pump ventoperably coupled to the vacuum system operable to the selectivelyrelease the chilled air stream for an aircraft cooling use as a coolingfluid.

Also disclosed is a method that includes driving rotation of a pluralityof components of a first air cycle machine through a gearbox operablycoupled to a shaft of a gas turbine engine to produce a cooling airstream based on a first engine bleed source of the gas turbine engine. Achilled air stream is output at a cryogenic temperature from a secondair cycle machine based on a second engine bleed source cooled by thecooling air stream of the first air cycle machine. The chilled airstream is condensed into liquid air for an aircraft use.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where a firstcompressor section of the first air cycle machine includes a firstcompressor wheel operably coupled to the gearbox, a first turbinesection of the first air cycle machine includes one or more turbinewheels operably coupled to the gearbox, and the second air cycle machineincludes a second compressor section and a second turbine section.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include selectively passing ableed air flow from the engine bleed source through an air-air heatexchanger interposed in fluid communication between the first enginebleed source and the first compressor wheel, and selectively passing thebleed air flow from the air-air heat exchanger to the through a fuel-airheat exchanger interposed in fluid communication between the air-airheat exchanger and a first turbine wheel of the first turbine section.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include selectively providingan output of the first turbine wheel to a first cooling use of theaircraft, and selectively providing the cooling air stream from a secondturbine wheel in fluid communication with the first turbine wheel to asecond cooling use and the second air cycle machine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include controlling aselection valve interposed in fluid communication between the air-airheat exchanger and the fuel-air heat exchanger to direct an output ofthe air-air heat exchanger to the first compressor wheel or the fuel-airheat exchanger, and mixing a plurality of flows from the firstcompressor wheel and a high pressure compressor of the gas turbineengine to provide a turbine cooling air input between the high pressurecompressor and a combustor of the gas turbine engine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include pre-cooling, by aheat exchanger system, an air flow from the second engine bleed sourceprior to entry into the second compressor section of the second aircycle machine, cooling, by the heat exchanger system, the air flow afterexiting the second compressor section, urging, by a cooling fan, a heatexchanger cooling flow across the heat exchanger system, the heatexchanger cooling flow comprising the cooling air stream of the firstair cycle machine, and providing the heat exchanger cooling flow as acooling source for the aircraft after crossing the heat exchangersystem.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include receiving the chilledair stream at a vacuum system and maintaining one or more exitconditions of the second turbine section, urging the liquid air, by aliquid air condensate pump system, through a feeder line, and collectingthe liquid air in a cryogenic liquid reservoir for the aircraft use.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include selectivelyreleasing, by a vacuum pump vent operably coupled to the vacuum system,the chilled air stream for an aircraft cooling use as a cooling fluid.

Further disclosed is a system for an aircraft. The system includes a gasturbine engine operable to produce thrust for the aircraft, a means forcryogenically cooling the aircraft, and a means for transferring energyfrom the gas turbine engine to the means for cryogenically cooling theaircraft.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means fortransferring energy is a gearbox operably coupled to a shaft of the gasturbine engine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forcryogenically cooling the aircraft is an engine-driven cryogenic coolingsystem that includes a first air cycle machine comprising a plurality ofcomponents operably coupled to the gearbox and configured to produce acooling air stream based on a first engine bleed source of the gasturbine engine, a second air cycle machine operable to output a chilledair stream at a cryogenic temperature based on a second engine bleedsource cooled by the cooling air stream of the first air cycle machine,and a liquid air collection system operable to condense the chilled airstream into liquid air for an aircraft use.

Disclosed is a gas turbine engine that includes a compressor section anda turbine section operably coupled to the compressor section. The gasturbine engine further includes a means for selectively releasing acooling fluid flow produced at a cryogenic temperature and a plumbingsystem in fluid communication with the means for selectively releasingthe cooling fluid flow. The plumbing system is configured to route thecooling fluid flow to one or more of the compressor section and theturbine section.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the plumbingsystem includes tubing routed through one or more components of the gasturbine engine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the plumbingsystem includes hollow ceramic lined vanes in one or more components ofthe gas turbine engine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the plumbingsystem is routed to deliver the cooling fluid flow to one or more rimcavities.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the plumbingsystem is routed to deliver the cooling fluid flow through a diffusercase.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the plumbingsystem is routed to deliver the cooling fluid flow at or in proximity toa tangential on-board injector flow.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the plumbingsystem is routed to deliver the cooling fluid flow to one or more buffercooling locations.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the plumbingsystem is routed to deliver the cooling fluid flow to one or more of: ahigh compressor flow, a turbine blade, and a turbine transition duct.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forselectively releasing the cooling fluid flow includes a cryogeniccooling system operable to generate liquid air on board the aircraft anda pump operable to urge the cooling fluid flow.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forselectively releasing the cooling fluid flow includes a liquid airstorage vessel.

Also disclosed is a method that includes determining, by a controller, aflight phase of an aircraft. The controller determines an operatingparameter of a gas turbine engine of the aircraft. Liquid air isselectively released from a liquid air source to a plumbing systemconfigured to route a cooling fluid flow from the liquid air source toone or more of a compressor section and a turbine section of the gasturbine engine based on either or both of the flight phase and theoperating parameter of the gas turbine engine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the plumbingsystem is routed to deliver the cooling fluid flow to one or more of: arim cavity, a tangential on-board injector flow, a buffer coolinglocation, a high compressor flow, a turbine blade, and a turbinetransition duct.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the liquid airsource includes a cryogenic cooling system operable to generate liquidair on board the aircraft and a pump operable to urge the cooling fluidflow.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the liquid airsource includes a liquid air storage vessel.

Also disclosed is a system for an aircraft. The system includes a gasturbine engine having a compressor section and a turbine sectionoperably coupled to the compressor section. The system also includes acryogenic cooling system operable to receive one or more air flows fromthe gas turbine engine and output a cooling fluid flow produced at acryogenic temperature. The system further includes a plumbing system influid communication with the cryogenic cooling system. The plumbingsystem is configured to route the cooling fluid flow from the cryogeniccooling system to one or more of the compressor section and the turbinesection.

Disclosed is a cryogenic cooling system for an aircraft. The cryogeniccooling system includes a first air cycle machine operable to output acooling air stream based on a first air source and a second air cyclemachine operable to output a chilled air stream at a cryogenictemperature based on a second air source cooled by the cooling airstream of the first air cycle machine. The cryogenic cooling system alsoincludes a means for collecting liquid air from an output of the secondair cycle machine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the first aircycle machine includes a first compressor section and a first turbinesection, and the second air cycle machine includes a second compressorsection and a second turbine section.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the firstcompressor section includes a first compressor wheel operably coupled toa first turbine wheel of the first turbine section and a first fan, andthe second compressor section includes a second compressor wheeloperably coupled to a second turbine wheel of the second turbine sectionand a second fan.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include a first heatexchanger system operable to pre-cool a first air flow from the firstair source prior to entry into the first compressor wheel and cool thefirst air flow after exiting the first compressor wheel, and a secondheat exchanger system operable to pre-cool a second air flow from thesecond air source prior to entry into the second compressor wheel andcool the second air flow after exiting the second compressor wheel.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the first fanis operable to urge a first heat exchanger cooling flow across the firstheat exchanger system, the second fan is operable to urge a second heatexchanger cooling flow across the second heat exchanger system, and thesecond heat exchanger cooling flow includes the cooling air stream ofthe first air cycle machine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include a first waterseparator in fluid communication with an output of the first compressorwheel and an input of the first turbine wheel, the first water separatoroperable to spray extracted water from the first air flow into the firstheat exchanger cooling flow, and a second water separator in fluidcommunication with an output of the second compressor wheel and an inputof the second turbine wheel, the second water separator operable tospray extracted water from the second air flow into the second heatexchanger cooling flow.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forcollecting liquid air is a liquid air collection system that includes avacuum system, a liquid air condensate pump system operable to urge theliquid air through a feeder line, and a cryogenic liquid reservoiroperably coupled to the feeder line.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include a cryogenic airseparator in fluid communication with the liquid air collection system,the cryogenic air separator operable to separate gaseous nitrogen andliquid oxygen from the liquid air collected by the liquid air collectionsystem, where the cryogenic air separator separates the gaseous nitrogenand liquid oxygen based on one or more of: a temperature-basedseparator, a stagnation plate-based separator, and a magnetic-basedseparator.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the gaseousnitrogen is supplied to a fuel system of the aircraft, and the liquidoxygen is supplied to one or more of: a cabin of the aircraft and acompressor stream of a gas turbine engine of the aircraft.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the liquid airis supplied as a cooling fluid to one or more of: an electric fanpropulsion motor of the aircraft, an environmental control system of theaircraft, a power system of the aircraft, and a gas turbine engine ofthe aircraft.

Also disclosed is a method that includes outputting a cooling air streamfrom a first air cycle machine based on a first air source. A chilledair stream is output at a cryogenic temperature from a second air cyclemachine based on a second air source cooled by the cooling air stream ofthe first air cycle machine. Liquid air is collected in a liquid aircollection system from an output of the second air cycle machine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include pre-cooling a firstair flow from the first air source through a first heat exchanger systemprior to entry into the first compressor wheel, cooling the first airflow through the first heat exchanger system after exiting the firstcompressor wheel, pre-cooling a second air flow from the second airsource through a second heat exchanger system prior to entry into thesecond compressor wheel and cool the second air flow after exiting thesecond compressor wheel, and cooling the second air flow through thesecond heat exchanger system after exiting the second compressor wheel.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include urging, by the firstfan, a first heat exchanger cooling flow across the first heat exchangersystem, and urging, by the second fan, a second heat exchanger coolingflow across the second heat exchanger system, where the second heatexchanger cooling flow includes the cooling air stream of the first aircycle machine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include separating, by acryogenic air separator, gaseous nitrogen and liquid oxygen from theliquid air collected by the liquid air collection system, where thecryogenic air separator separates the gaseous nitrogen and liquid oxygenbased on one or more of: a temperature-based separator, a stagnationplate-based separator, and a magnetic-based separator.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include supplying the gaseousnitrogen to a fuel system of an aircraft, and supplying the liquidoxygen to one or more of: a cabin of the aircraft and a compressorstream of a gas turbine engine of the aircraft.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include supplying the liquidair as a cooling fluid to one or more of: an electric fan propulsionmotor of an aircraft, an environmental control system of the aircraft, apower system of the aircraft, and a gas turbine engine of the aircraft.

A system for an aircraft includes a gas turbine engine operable toproduce thrust for the aircraft and a cryogenic cooling system operableto receive one or more air flows from the gas turbine engine and outputa chilled air stream at a cryogenic temperature. A liquid air collectionsystem is in fluid communication with an output of the cryogenic coolingsystem and operable to receive the chilled air stream. A cryogenic airseparator is in fluid communication with the liquid air collectionsystem, where the cryogenic air separator is operable to separategaseous nitrogen and liquid oxygen from liquid air collected by theliquid air collection system.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the gaseousnitrogen is supplied to a fuel system of the aircraft, and the liquidoxygen is supplied to one or more of: a cabin of the aircraft and acompressor stream of the gas turbine engine of the aircraft.

Disclosed is a propulsion system that includes an electric fanpropulsion motor with a plurality of propulsion motor windings. Thepropulsion system also includes a means for controlling a flow rate of aworking fluid through a cryogenic working fluid flow control assembly tothe propulsion motor windings.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the cryogenicworking fluid flow control assembly includes a manifold and a purgevalve proximate to a housing of the electric fan propulsion motor.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forcryogenic cooling includes a cryogenic liquid reservoir and a controlleroperable to supply a pre-cooling flow of the working fluid from thecryogenic liquid reservoir through the cryogenic working fluid flowcontrol assembly to the propulsion motor windings, increase a flow rateof the working fluid to supply a full cooling flow from the cryogenicliquid reservoir through the cryogenic working fluid flow controlassembly to the propulsion motor windings, cycle the purge valve to venta gaseous accumulation of the working fluid, and deliver the workingfluid in a liquid state to the propulsion motor windings duringoperation of the electric fan propulsion motor.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the cryogenicworking fluid flow control assembly includes a main flow control valveoperable to control the flow rate of the working fluid through a primarycooling line of the cryogenic working fluid flow control assembly to thepropulsion motor windings.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the main flowcontrol valve is a variable position valve operable to transitionbetween a closed position, a partially opened position to supply thepre-cooling flow, and a fully opened position to supply the full coolingflow.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the cryogenicworking fluid flow control assembly includes a bypass cooling line and abypass flow control valve configured to selectively provide thepre-cooling flow as a bypass cooling flow around the main flow controlvalve.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include one or moretemperature sensors, where the controller is operable to control changesin the flow rate of the working fluid and timing of opening and closingthe purge valve based on temperature data from the one or moretemperature sensors.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include one or more pressuresensors, where the controller is operable to control changes in the flowrate of the working fluid and timing of opening and closing the purgevalve based on pressure data from the one or more pressure sensors.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include a speed of theelectric fan propulsion motor is limited responsive to confirmingwhether the working fluid is reaching the propulsion motor windings inthe liquid state.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the controlleris operable to decrease a flow rate of the working fluid from the fullcooling flow to a reduced cooling flow prior to disabling a flow of theworking fluid from the cryogenic liquid reservoir through the cryogenicworking fluid flow control assembly to the propulsion motor windings.

Also disclosed is a method that can include supplying a pre-cooling flowof a working fluid from a cryogenic liquid reservoir through a cryogenicworking fluid flow control assembly to a plurality of propulsion motorwindings of an electric fan propulsion motor. A flow rate of the workingfluid is increased to supply a full cooling flow from the cryogenicliquid reservoir through the cryogenic working fluid flow controlassembly to the propulsion motor windings. A purge valve of thecryogenic working fluid flow control assembly is cycled to vent agaseous accumulation of the working fluid. The working fluid isdelivered in a liquid state to the propulsion motor windings duringoperation of the electric fan propulsion motor.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include modifying a positionof a main flow control valve to control the flow rate of the workingfluid through a primary cooling line of the cryogenic working fluid flowcontrol assembly to the propulsion motor windings.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the main flowcontrol valve is a variable position valve operable to transitionbetween a closed position, a partially opened position to supply thepre-cooling flow, and a fully opened position to supply the full coolingflow.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include opening a bypass flowcontrol valve to provide the pre-cooling flow as a bypass cooling flowthrough a bypass cooling line around the main flow control valve.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include changing the flowrate of the working fluid and timing of opening and closing the purgevalve based on temperature data from one or more temperature sensors.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include changing the flowrate of the working fluid and timing of opening and closing the purgevalve based on pressure data from one or more pressure sensors.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include limiting a speed ofthe electric fan propulsion motor responsive to confirming whether theworking fluid is reaching the propulsion motor windings in the liquidstate.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include decreasing a flowrate of the working fluid from the full cooling flow to a reducedcooling flow prior to disabling a flow of the working fluid from thecryogenic liquid reservoir through the cryogenic working fluid flowcontrol assembly to the propulsion motor windings.

Also disclosed is a propulsion system including at least one gas turbineengine, at least one electric generator operable to produce an electriccurrent responsive to rotation driven by the at least one gas turbineengine, an electric fan propulsion motor including a plurality ofpropulsion motor windings selectively powered responsive to the electriccurrent, and a cryogenic cooling system including a cryogenic liquidreservoir and a cryogenic working fluid flow control assembly in fluidcommunication with the propulsion motor windings. The cryogenic coolingsystem is operable to control a flow rate of a working fluid through thecryogenic working fluid flow control assembly to the propulsion motorwindings.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the cryogeniccooling system operation is supplemented by a non-cryogenic cooling flowto the propulsion motor windings.

Disclosed is a ground-based cryogenic cooling system that includes ameans for cooling an airflow and producing chilled air responsive to apower supply and a liquid air condensate pump system operable tocondense the chilled air into liquid air and urge the liquid air througha feeder line. A cryogenic cartridge includes a coupling interfaceconfigured to detachably establish fluid communication with the feederline and a cryogenic liquid reservoir configured to store the liquid airunder pressure.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forcooling the airflow includes a compressor configured to receive theairflow and produce compressed air, an electric motor operable to driverotation of the compressor responsive to the power supply, a heatexchanger system in fluid communication with the compressor andconfigured to cool the compressed air, a means for separating water fromthe compressed air to produce dried cool air, and a turbine assemblyincluding one or more turbines in fluid communication with the means forseparating water, the turbine assembly configured to expand the driedcool air and produce the chilled air.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the means forseparating water includes a condenser.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the powersupply is an electric power supply from a renewable power sourceincluding one or more of: a solar array, a wind turbine system, and arechargeable battery system.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the cryogeniccartridge includes a rapid release component operable to depressurizethe cryogenic liquid reservoir upon impact.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include a filling stationoperable to pressurize and store the liquid air in a plurality ofcryogenic cartridges.

Also disclosed is a method that can include operating a ground-basedcryogenic cooling system to produce a volume of liquid air, pressurizingand storing the liquid air in a cryogenic cartridge, coupling thecryogenic cartridge to a cryogenic liquid distribution system on anaircraft, and selectively releasing the liquid air from the cryogeniccartridge through the cryogenic liquid distribution system for anaircraft use.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include producing compressedair by a compressor responsive to rotation driven by an electric motor,cooling the compressed air through a heat exchanger system, removingwater from the cooled compressed air to produce dried cool air, andexpanding the dried cool air through a turbine assembly to producechilled air.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include condensing thechilled air into the liquid air and urging the liquid air through afeeder line into the cryogenic cartridge.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the cryogeniccartridge includes a coupling interface configured to detachablyestablish fluid communication with the feeder line and a cryogenicliquid reservoir configured to store the liquid air under pressure.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the cryogeniccartridge includes a rapid release component operable to depressurizethe cryogenic liquid reservoir upon impact.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the electricmotor is powered by a renewable power source including one or more of: asolar array, a wind turbine system, and a rechargeable battery system.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the aircraftuse includes cryogenically cooling an electric motor.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the aircraftuse includes cooling one or more components of a gas turbine engine.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the aircraftuse includes cooling power electronics of the aircraft.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include passing the liquidair through a gas separation system to produce gaseous nitrogen andliquid oxygen, providing the gaseous nitrogen to a fuel tank inertingsystem, and providing the liquid oxygen to either or both of abreathable oxygen system and a combustion enhancement system.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include controlling anon-board cryogenic cooler to at least partially recharge the cryogeniccartridge during aircraft operation.

Also disclosed is a cryogenic system for an aircraft. The cryogenicsystem can include a cryogenic liquid distribution system including oneor more cryogenic fluid flow paths. The cryogenic system can alsoinclude a cryogenic cartridge having a coupling interface configured todetachably establish fluid communication with the cryogenic liquiddistribution system and a cryogenic liquid reservoir configured to storeliquid air under pressure as a cryogenic working fluid. The cryogenicsystem can also include one or more cryogenic usage systems in fluidcommunication with the one or more cryogenic fluid flow paths andconfigured to selectively receive the cryogenic working fluid.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include where the cryogeniccartridge includes a rapid release component operable to depressurizethe cryogenic liquid reservoir upon impact.

In addition to one or more of the features described above or below, oras an alternative, further embodiments may include an on-board cryogeniccooler operable to at least partially recharge the cryogenic cartridgeduring aircraft operation.

A technical effect of systems and methods can be achieved by providing achilled working fluid generation and separation for on-board uses on anaircraft as described herein. A technical effect of systems and methodscan be achieved by providing a cryogenic cooling system for an aircraftto create liquid air and/or separate oxygen and nitrogen supplies foron-board uses as described herein. A technical effect of systems andmethods can be achieved by providing an engine-driven cryogenic coolingsystem for an aircraft to create liquid air for on-board cryogenic usesand/or to supply cooling air for on-board use as described herein. Atechnical effect of systems and methods can be achieved by providingcryogenic cooling to components of a gas turbine engine as describedherein. A technical effect of systems and methods can be achieved byproviding a cryogenic cooling system for an aircraft to create liquidair for on-board cryogenic uses and/or to supply isolated sources ofgaseous nitrogen and liquid oxygen for on-board use as described herein.A technical effect of systems and methods can be achieved by controllinga flow rate of a working fluid through a cryogenic working fluid flowcontrol assembly to propulsion motor windings of an electric fanpropulsion motor for efficient cryogenically cooled operation of theelectric fan propulsion motor as described herein. A technical effect ofsystems and methods can be achieved by generating and storing liquid airin one or more cryogenic cartridges using a ground-based system andproviding the cryogenic cartridges for use on an aircraft as describedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 is a schematic illustration of a gas turbine engine in accordancewith an embodiment of the disclosure;

FIG. 2 is a schematic illustration of an aircraft including a propulsionsystem in accordance with an embodiment of the disclosure;

FIG. 3 is a schematic illustration of a cryogenic cooling system inaccordance with an embodiment of the disclosure;

FIG. 4 is a schematic illustration of a cryogenic air separator inaccordance with an embodiment of the disclosure;

FIG. 5 is a schematic illustration of a cryogenic air separator inaccordance with an embodiment of the disclosure;

FIG. 6 is a schematic illustration of a cryogenic air separator inaccordance with an embodiment of the disclosure;

FIG. 7 is a flow chart illustrating a method in accordance with anembodiment of the disclosure;

FIG. 8 is a flow chart illustrating a method in accordance with anembodiment of the disclosure;

FIG. 9 is a schematic illustration of an aircraft including a propulsionsystem in accordance with an embodiment of the disclosure;

FIG. 10 is a schematic illustration of an engine-driven cryogeniccooling system in accordance with an embodiment of the disclosure;

FIG. 11 is a flow chart illustrating a method in accordance with anembodiment of the disclosure;

FIG. 12 is a schematic illustration of a cryogenic cooling system inaccordance with an embodiment of the disclosure;

FIG. 13 is a plot of relative internal temperature changes vs. time fora various flight phases in accordance with an embodiment of thedisclosure;

FIG. 14 is a schematic illustration of a gas turbine engine component inaccordance with an embodiment of the disclosure;

FIG. 15 is a schematic illustration of portions of a gas turbine engineconfigured to receive a cooling fluid flow in accordance with anembodiment of the disclosure;

FIG. 16 is a schematic illustration of portions of a gas turbine engineconfigured to receive a cooling fluid flow in accordance with anembodiment of the disclosure;

FIG. 17 is a schematic illustration of portions of a gas turbine engineconfigured to receive a cooling fluid flow in accordance with anembodiment of the disclosure;

FIG. 18 is a flow chart illustrating a method in accordance with anembodiment of the disclosure.

FIG. 19 is a schematic illustration of a cryogenic cooling system inaccordance with an embodiment of the disclosure;

FIG. 20 is a schematic illustration of a cryogenic air separator inaccordance with an embodiment of the disclosure;

FIG. 21 is a schematic illustration of a cryogenic air separator inaccordance with an embodiment of the disclosure;

FIG. 22 is a schematic illustration of a cryogenic air separator inaccordance with an embodiment of the disclosure;

FIG. 23 is a flow chart illustrating a method in accordance with anembodiment of the disclosure;

FIG. 24 is a schematic illustration of a cryogenic cooling system inaccordance with an embodiment of the disclosure;

FIG. 25 is a schematic illustration of a cryogenic cooling system inaccordance with an embodiment of the disclosure;

FIG. 26 is a state transition diagram in accordance with an embodimentof the disclosure;

FIG. 27 is a system response plot in accordance with an embodiment ofthe disclosure;

FIG. 28 is a system response plot in accordance with an embodiment ofthe disclosure;

FIG. 29 is a system response plot in accordance with an embodiment ofthe disclosure;

FIG. 30 is a flow chart illustrating a method in accordance with anembodiment of the disclosure;

FIG. 31 is a schematic illustration of a ground-based cryogenic liquidgeneration system in accordance with an embodiment of the disclosure;

FIG. 32 is a schematic illustration of a filling station in accordancewith an embodiment of the disclosure;

FIG. 33 is a schematic illustration of a cryogenic system for anaircraft in accordance with an embodiment of the disclosure;

FIG. 34 is a schematic illustration of an electric motor cryogeniccooling system in accordance with an embodiment of the disclosure;

FIG. 35 is a schematic illustration of an on-board liquid air generationsystem in accordance with an embodiment of the disclosure;

FIG. 36 is a schematic illustration of a gas separation system inaccordance with an embodiment of the disclosure; and

FIG. 37 is a flow chart illustrating a method in accordance with anembodiment of the disclosure.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures.

FIG. 1 schematically illustrates a gas turbine engine 20. The gasturbine engine 20 is disclosed herein as a two-spool turbofan thatgenerally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. The fan section 22 drivesair along a bypass flow path B in a bypass duct, while the compressorsection 24 drives air along a core flow path C for compression andcommunication into the combustor section 26 then expansion through theturbine section 28. Although depicted as a two-spool turbofan gasturbine engine in the disclosed non-limiting embodiment, it should beunderstood that the concepts described herein are not limited to usewith two-spool turbofans as the teachings may be applied to other typesof turbine engines including three-spool architectures.

The exemplary engine 20 generally includes a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A relative to an engine static structure 36 viaseveral bearing systems 38. It should be understood that various bearingsystems 38 at various locations may alternatively or additionally beprovided, and the location of bearing systems 38 may be varied asappropriate to the application.

The low speed spool 30 generally includes an inner shaft 40 thatinterconnects a fan 42, a low pressure compressor 44 and a low pressureturbine 46. The inner shaft 40 is connected to the fan 42 through aspeed change mechanism, which in exemplary gas turbine engine 20 isillustrated as a geared architecture 48 to drive the fan 42 at a lowerspeed than the low speed spool 30. The high speed spool 32 includes anouter shaft 50 that interconnects a high pressure compressor 52 and highpressure turbine 54. A combustor 56 is arranged in exemplary gas turbine20 between the high pressure compressor 52 and the high pressure turbine54. An engine static structure 36 is arranged generally between the highpressure turbine 54 and the low pressure turbine 46. The engine staticstructure 36 further supports bearing systems 38 in the turbine section28. The inner shaft 40 and the outer shaft 50 are concentric and rotatevia bearing systems 38 about the engine central longitudinal axis Awhich is collinear with their longitudinal axes.

The core airflow is compressed by the low pressure compressor 44 thenthe high pressure compressor 52, mixed and burned with fuel in thecombustor 56, then expanded over the high pressure turbine 54 and lowpressure turbine 46. The turbines 46, 54 rotationally drive therespective low speed spool 30 and high speed spool 32 in response to theexpansion. It will be appreciated that each of the positions of the fansection 22, compressor section 24, combustor section 26, turbine section28, and fan drive gear system 48 may be varied. For example, gear system48 may be located aft of combustor section 26 or even aft of turbinesection 28, and fan section 22 may be positioned forward or aft of thelocation of gear system 48.

The engine 20 in one example is a high-bypass geared aircraft engine. Ina further example, the engine 20 bypass ratio is greater than about six(6), with an example embodiment being greater than about ten (10), thegeared architecture 48 is an epicyclic gear train, such as a planetarygear system or other gear system, with a gear reduction ratio of greaterthan about 2.3 and the low pressure turbine 46 has a pressure ratio thatis greater than about five. In one disclosed embodiment, the engine 20bypass ratio is greater than about ten (10:1), the fan diameter issignificantly larger than that of the low pressure compressor 44, andthe low pressure turbine 46 has a pressure ratio that is greater thanabout five 5:1. Low pressure turbine 46 pressure ratio is pressuremeasured prior to inlet of low pressure turbine 46 as related to thepressure at the outlet of the low pressure turbine 46 prior to anexhaust nozzle. The geared architecture 48 may be an epicycle geartrain, such as a planetary gear system or other gear system, with a gearreduction ratio of greater than about 2.3:1. It should be understood,however, that the above parameters are only exemplary of one embodimentof a geared architecture engine and that the present disclosure isapplicable to other gas turbine engines including direct driveturbofans.

A significant amount of thrust is provided by the bypass flow B due tothe high bypass ratio. The fan section 22 of the engine 20 is designedfor a particular flight condition—typically cruise at about 0.8Mach andabout 35,000 feet (10,688 meters). The flight condition of 0.8 Mach and35,000 ft (10,688 meters), with the engine at its best fuelconsumption—also known as “bucket cruise Thrust Specific FuelConsumption (‘TSFC’)”—is the industry standard parameter of lbm of fuelbeing burned divided by lbf of thrust the engine produces at thatminimum point. “Low fan pressure ratio” is the pressure ratio across thefan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The lowfan pressure ratio as disclosed herein according to one non-limitingembodiment is less than about 1.45. “Low corrected fan tip speed” is theactual fan tip speed in ft/sec divided by an industry standardtemperature correction of [(Tram ° R)/(518.7° R)]^(0.5). The “Lowcorrected fan tip speed” as disclosed herein according to onenon-limiting embodiment is less than about 1150 ft/second (350.5 m/sec).

FIG. 2 schematically illustrates an aircraft 100 with a propulsionsystem 102. The propulsion system 102 can include one or more gasturbine engines 20 of FIG. 1 and a fuel system 105 operable to providecombustible fuel to the gas turbine engines 20. The gas turbine engines20 can provide thrust for the aircraft 100 and power for engineaccessories. In the example of FIG. 2, the aircraft 100 includes a pairof gas turbine engines 20. Fuel from the fuel system 105 is combusted toproduce a compressor stream 107 within each of the gas turbine engines20. The gas turbine engines 20 can also provide compressed air for anenvironmental control system 109 to condition a cabin 112 of theaircraft 100, and other uses. The aircraft 100 can also include varioussystems, such as electronics 115 for control operations, monitoringfunctions, electric power generation, and the like. In embodiments, theaircraft 100 includes one or more cryogenic cooling systems 200 (e.g.,one per gas turbine engine 20) as further described and depicted in FIG.3. It will be understood that the aircraft 100 includes additionalsystems not depicted in FIG. 2.

FIG. 3 depicts a cryogenic cooling system 200 according to an embodimentand is described with continued reference to FIGS. 1 and 2. Thecryogenic cooling system 200 is an example of a means for chilling anengine bleed air flow 252 from an engine bleed source 251 of a gasturbine engine 20. The cryogenic cooling system 200, plumbing system204, and engine bleed source 251 can collectively form a system of theaircraft 100. Various station locations of the gas turbine engine 20 canbe selected as the engine bleed source 251 depending on desiredtemperature and pressure characteristics of the engine bleed air flow252 received at the cryogenic cooling system 200. For example, if lowertemperature and pressure characteristics of the engine bleed air flow252 are desired, the engine bleed source 251 can be between the fan 42and the low pressure compressor 44 or at a location of the low pressurecompressor 44. If higher temperature and pressure characteristics of theengine bleed air flow 252 are desired, the engine bleed source 251 canbe between the low pressure compressor 44 and the high pressurecompressor 52, at a location of the high pressure compressor 52, orbetween the high pressure compressor 52 and the combustor 56, forexample.

The cryogenic cooling system 200 can include a cryogenic cooler 242operable to chill the engine bleed air flow 252 and produce a workingfluid flow 206 for distribution through a plumbing system 204 to coolone or more components 208 of the aircraft 100. In some embodiments, theworking fluid flow 206 is chilled below the boiling point of air toproduce liquid air. In other embodiments, the working fluid flow 206 ischilled to produce a chilled working fluid at a temperature below theboiling point of oxygen and above the boiling point of nitrogen withrespect to the pressure of the working fluid flow 206. Liquid air may bemore expensive to produce but easier to pump than a mixed-state or allgas flow. The plumbing system 204 can include tubing that is insulatedand/or includes multiple walls to reduce heat transfer. Further, theplumbing system 204 can be routed through one or more components of thegas turbine engine 20 and may be internal and/or external to portions ofthe gas turbine engine 20 and routed through the aircraft 100 as needed.

The cryogenic cooling system 200 is operable to control a flow rate ofthe working fluid flow 206 through the plumbing system 204 to one ormore components 208 of the aircraft 100. The plumbing system 204 caninclude one or more pumps, such as pump 210 in fluid communication witha feeder line 240, and the plumbing system 204 can include one or morelines 215, 216, 217, 218, and valves 212, 214. The pump 210 is anexample of a means for providing the working fluid flow 206, such asliquid air or a chilled working fluid, for an aircraft use through theplumbing system 204. The pump 210 is operable to urge the working fluidflow 206 through the plumbing system 204 for cooling and/or increasingairflow to one or more components 208 of the aircraft 100 as one or moreaircraft uses. Examples of aircraft uses can include cooling componentsof the gas turbine engine 20, environmental control system 109, cabin112, electronics 115, and/or other such components and systems. Theworking fluid flow 206 can also be used for components 208 that maybenefit from an increased air flow, such as pneumatic systems.

In embodiments, a combination of valves 212, 214 can be used to controlthe flow rate of the working fluid flow 206. For example, control valve212 is operable to control the flow rate of the working fluid flow 206into the plumbing system 204. One or more control valves, such as valve214, can be used to direct a portion of the working fluid flow 206(indicated as flow 281) to a cryogenic air separator 220 that provides ameans for separating gaseous nitrogen and liquid oxygen from the workingfluid flow 206. For example, the cryogenic air separator 220 mayseparate liquid air or a chilled working fluid into a gaseous nitrogensupply 222 and a liquid oxygen supply 224. Line 217 may provide gaseousnitrogen from the cryogenic air separator 220 for the gaseous nitrogensupply 222. Line 218 may provide liquid oxygen from the cryogenic airseparator 220 for the liquid oxygen supply 224. In some embodiments, apump 226 can be included at either or both lines 217, 218. In theexample of FIG. 3, pump 226 may efficiently urge liquid oxygen throughline 218 due to being in a liquid state.

The gaseous nitrogen supply 222 can be used, for example, to sparge fuelin the fuel system 105 to remove oxygen. As such, the gaseous nitrogensupply 222 may obviate the need for a fuel deoxygenation system based onmembranes. The nitrogen from the gaseous nitrogen supply 222 can also oralternatively be used to supply inert gas to tanks of the fuel system105, lowering a combustion risk within the fuel system 105, andeliminating the need for onboard inert gas generating systems on theaircraft 100. As another example, nitrogen from the gaseous nitrogensupply 222 can be injected back into the gas turbine engines 20downstream of the combustor 56, for instance, at or proximate to thehigh pressure turbine 54. The addition of nitrogen from the gaseousnitrogen supply 222 at the high pressure turbine 54 can provide coolingand also reduce the risk of combustion occurring in the high pressureturbine 54 should any fuel reach that location. Various instrumentationor equipment of the aircraft 100 that may benefit from an isolatedsource of nitrogen may also or alternatively receive nitrogen from thegaseous nitrogen supply 222. Other uses of the gaseous nitrogen supply222 are contemplated, and the description provided herein merelyrepresents several of many possible example uses.

The liquid oxygen supply 224 can be used, for example, to provideintercooling to the gas turbine engines 20. Injection of liquid or coldoxygen in the compressor stream 107 can enhance oxygen concentrationupstream from the combustor 56, allowing for higher combustiontemperatures without a requirement for the compression and theassociated parasitic losses of additional gas volume. Oxygen injectioncan further enhance thermodynamic efficiency in a Brayton cycle machine.For example, given that oxygen is a minority constituent in the air by⅕, just 10% cooled cooling air can result in up to a 50% increase inoxygen available for combustion. Further, oxygen from the liquid oxygensupply 224 can be selectively injected into the gas turbine engine 20for reductions in acceleration time by providing additional oxidizerindependent of the angular moment of inertia associated with spooling upthe rotating compression machinery. Further, oxygen from the liquidoxygen supply 224 can be used to supplement or be a primary source ofbreathable oxygen after conditioning (e.g., temperature and pressurecontrol) for the aircraft 100. Various instrumentation or equipment ofthe aircraft 100 that may benefit from an isolated source of oxygen mayalso or alternatively receive oxygen from the liquid oxygen supply 224.Other uses of the liquid oxygen supply 224 are contemplated, and thedescription provided herein merely represents several of many possibleexample uses.

In some embodiments, the cryogenic cooler 242 can include one or moreair cycle machines 244 operable to compress, chill, expand, pump, andcondense an air flow to produce liquid air or a chilled working fluidfor use on the aircraft 100. As one example, the cryogenic cooler 242can include a heat exchanger system 246 operable to receive a coolingair intake 248. A compressor 250 can receive an engine bleed air flow252 from the gas turbine engine 20 of FIG. 1 as an air flow. Compressedair 254 output by the compressor 250 can pass through the heat exchangersystem 246 to at least one turbine 256 as a cooled flow 258 to a vacuumsystem 260 and a condensate pump system 262 that urges the working fluidflow 206 resulting from chilling the engine bleed air flow 252 throughthe feeder line 240. The compressor 250 and the at least one turbine 256may be mechanically linked by a coupling 264, such as a shaft. In someembodiments, the compressor 250 and the at least one turbine 256 are notphysically coupled. The compressor 250 can be driven mechanically by thegas turbine engine 20 of FIG. 1 and/or electrically using an electricmotor (not depicted). Although one example of the cryogenic cooler 242is depicted in the example of FIG. 3, it will be understood thatadditional elements and modifications are contemplated, such as two ormore turbine wheels, recirculation paths, water separation, one or morefan sections, intermediate taps, relief valves, and/or other suchelements known in the art

A controller 290 can interface with and control multiple elements of thecryogenic cooling system 200, such as valve states, flow rates,pressures, temperatures, rotational state of one or more air cyclemachines 244, and the like. In an embodiment, the controller 290includes a memory system 292 to store instructions that are executed bya processing system 294 of the controller 290. The executableinstructions may be stored or organized in any manner and at any levelof abstraction, such as in connection with a controlling and/ormonitoring operation of the cryogenic cooling system 200. The processingsystem 294 can include one or more processors that can be any type ofcentral processing unit (CPU), including a microprocessor, a digitalsignal processor (DSP), a microcontroller, an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA), orthe like. Also, in embodiments, the memory system 292 may include randomaccess memory (RAM), read only memory (ROM), or other electronic,optical, magnetic, or any other computer readable medium onto which isstored data and control algorithms in a non-transitory form.

FIG. 4 depicts a cryogenic air separator 300 as one example of thecryogenic air separator 220 of FIG. 3 in accordance with an embodiment.The cryogenic air separator 300 includes a separation vessel 302 with atleast one input port 304, at least one gaseous nitrogen output port 306,and at least one liquid oxygen output port 308. The input port 304 isoperable to receive the flow 281 from the cryogenic cooling system 200of FIG. 3. In some embodiments, the temperature of the flow 281 can bebelow the boiling points of nitrogen, oxygen, and other constituents ofair upon reaching the input port 304 as substantially liquid air. Inother embodiments, the flow 281 may reach the input port 304 at atemperature below the boiling point of oxygen and above the boilingpoint of nitrogen for the respective pressure. The separation vessel 302can be sized, located, and otherwise temperature controlled to allownitrogen to boil off or otherwise separate from the flow 281 through thegaseous nitrogen output port 306 as gaseous nitrogen 305 to the gaseousnitrogen supply 222 while liquid oxygen 307 remains and flows out of theliquid oxygen output port 308 to the liquid oxygen supply 224. Theseparation in the cryogenic air separator 300 can be impact plate-based,where upon the flow 281 striking an impact plate 310 positionedproximate to the input port 304, a flow direction of the flow 281 isaltered such that gaseous nitrogen 305 separates (e.g., rises) from theliquid oxygen 307. Due to differences in the boiling points of nitrogenand oxygen, nitrogen can be in a gaseous state while oxygen (andpotentially argon) remains liquefied where temperature conditions areabove the boiling point of nitrogen but below the boiling point ofoxygen. The pressure of the flow 281 can be set/adjusted (e.g., bycontroller 290 of FIG. 1) to match the separation performance propertiesof the cryogenic air separator 300, as liquid/gas state is a function ofpressure and temperature. Although the example of FIG. 4 includes asingle separation vessel 302, it will be understood that otherconfigurations can be implemented, such as a series of separationvessels 302.

FIG. 5 depicts a cryogenic air separator 400 as another example of thecryogenic air separator 220 of FIG. 3 in accordance with an embodiment.The cryogenic air separator 400 includes a separation vessel 402 with atleast one input port 404, at least one gaseous nitrogen output port 406,at least one liquid oxygen output port 408, and a stagnation plate 410.The cryogenic air separator 400 is referred to as a stagnationplate-based separator, in that the flow 281 received at the input port404 from the cryogenic cooling system 200 of FIG. 3 strikes thestagnation plate 410 to enhance separation of gaseous nitrogen for thegaseous nitrogen supply 222 and liquid oxygen for the liquid oxygensupply 224. The stagnation plate 410 can include variations in curvatureand flow paths, resulting in trapping regions that alter the flowvelocity and pressure of the flow 281. In regions where the flowvelocity and pressure change, a partial state change can occur wheregaseous nitrogen separates from the flow 281 and is output from thegaseous nitrogen output port 406 for the gaseous nitrogen supply 222,while the remaining liquid retains oxygen (and potentially argon) inliquid oxygen is output from the liquid oxygen output port 408 for theliquid oxygen supply 224. Although one example configuration is depictedin FIG. 5, it will be understood that various configurations of thestagnation plate 410 can be implemented in embodiments.

FIG. 6 depicts a cryogenic air separator 500 as another example of thecryogenic air separator 220 of FIG. 3 in accordance with an embodiment.The cryogenic air separator 500 includes a separation vessel 502 with atleast one input port 504, at least one gaseous nitrogen output port 506,at least one liquid oxygen output port 508, and a magnetic fieldgenerator 510. The cryogenic air separator 500 is referred to as amagnetic-based separator. The flow 281 received at the input port 504from the cryogenic cooling system 200 of FIG. 3 may initially separatedue to the pressure/temperature conditions within the separation vessel502 and differences in the boiling points of nitrogen and oxygen. Thecontroller 290 of FIG. 2 may apply a magnetic field by controlling aflow of electric current through the magnetic field generator 510 (e.g.,coils of wires). The magnetic field generator 510 can be locatedproximate to the oxygen output port 508 to take advantage of theparamagnetism of the liquid oxygen to attract/urge the liquid oxygentoward the liquid oxygen output port 508 for the liquid oxygen supply224, while gaseous nitrogen rises to the gaseous nitrogen output port506 for the gaseous nitrogen supply 222. In some embodiments, themagnetic field generator 510 can include one or more permanent magnets.Although one example configuration is depicted in FIG. 6, it will beunderstood that various configurations of the magnetic field generator510 are contemplated. Further embodiments can combine elements of thecryogenic air separators 300-500 of FIGS. 4-6.

FIG. 7 is a flow chart illustrating a method 600 in accordance with anembodiment. The method 600 of FIG. 7 is described in reference to FIGS.1-7 and may be performed with an alternate order and include additionalsteps. The method 600 can be performed, for example, by the cryogeniccooling system 200 of FIG. 3. In the example of FIG. 7, the method 600produces liquid air as the working fluid flow 206.

At block 602, an engine bleed air flow 252 can be provided from anengine bleed source 251 of a gas turbine engine 20 to the cryogeniccooling system 200. At block 604, the engine bleed air flow 252 ischilled using the cryogenic cooling system 200 to produce liquid air asa working fluid flow 206. Pre-cooling of the engine bleed air flow 252can be performed using a heat exchanger system 246. The engine bleed airflow 252 can be compressed as compressed air 254 by a compressor 250 ofthe cryogenic cooling system 200. Expanding and cooling of thecompressed air 254 can be performed by at least one turbine 256 of thecryogenic cooling system 200 to produce a cooled flow 258. A cooling airintake 248 can be received at the heat exchanger system 246, and theheat exchanger system 246 can further cool the compressed air 254 priorto reaching the at least one turbine 256. The cooling air intake 248 canbe ambient air, ram air, or other air sources that are cooler than thecompressed air 254, for example. In some embodiments, liquid air iscondensed from the cooled flow 258.

At block 606, the liquid air in the working fluid flow 206 can be pumpedby the pump 210 for an aircraft use. The pump 210 can urge the liquidair through a feeder line 240 to cool and/or increase an air flow to oneor more components 208 of the aircraft 100.

All or a portion of the working fluid flow 206 can be provided as flow281 to a cryogenic air separator 220 operable to separate gaseousnitrogen from the liquid air as a gaseous nitrogen supply 222. Thecryogenic air separator 220 can also separate liquid oxygen from theliquid air as a liquid oxygen supply 224. At least a portion of thegaseous nitrogen supply 222 can be provided to one or more of: a fuelsystem 105 of the aircraft 100 and a location downstream of a combustor56 of the gas turbine engine 20. At least a portion of the liquid oxygensupply 224 can be provided to one or more of: a cabin 112 of theaircraft 100 and a compressor stream 107 of the gas turbine engine 20.

FIG. 8 is a flow chart illustrating a method 700 in accordance with anembodiment. The method 700 of FIG. 8 is described in reference to FIGS.1-8 and may be performed with an alternate order and include additionalsteps. The method 700 can be performed, for example, by the cryogeniccooling system 200 of FIG. 3. In the example of FIG. 8, the method 700produces a chilled working fluid (e.g., warmer than liquid air) as theworking fluid flow 206.

At block 702, an engine bleed air flow 252 can be provided from anengine bleed source 251 of a gas turbine engine 20 to a cryogeniccooling system 200. At block 704, the engine bleed air flow 252 can bechilled using the cryogenic cooling system 200 to produce a chilledworking fluid as the working fluid flow 206 at a temperature below aboiling point of oxygen and above a boiling point of nitrogen. Theengine bleed air flow 252 can be compressed as compressed air 254 by acompressor 250 of the cryogenic cooling system 200. Expanding andcooling of the compressed air 254 can be performed by at least oneturbine 256 of the cryogenic cooling system 200 to produce as thechilled working fluid. The chilled working fluid may be provided as theworking fluid flow 206 for an aircraft use. The aircraft use can includecooling and/or increasing an air flow to one or more components 208 ofthe aircraft 100.

At block 706, gaseous nitrogen can be separated from the chilled workingfluid as a gaseous nitrogen supply. For example, all or a portion of theworking fluid flow 206 can be provided as flow 281 to a cryogenic airseparator 220 operable to separate gaseous nitrogen from the chilledworking fluid as a gaseous nitrogen supply 222. At block 708, liquidoxygen can be separated from the chilled working fluid as a liquidoxygen supply 224. In embodiments, separating gaseous nitrogen andliquid oxygen can be performed using an impact plate-based separator,such as cryogenic air separator 300, including an impact plate 310positioned proximate to an input port 304 to alter a flow direction ofthe chilled working fluid as the flow 281. Separating gaseous nitrogenand liquid oxygen can alternatively be performed using a stagnationplate-based separator, such as cryogenic air separator 400, including astagnation plate 410 with variations in curvature and flow paths toalter a flow velocity and pressure of the chilled working fluid as theflow 281. Separating gaseous nitrogen and liquid oxygen may also beperformed using a magnetic-based separator, such as cryogenic airseparator 500, including a magnetic field generator 510 operable toproduce a magnetic field to attract the liquid oxygen towards a liquidoxygen output port 508.

FIG. 9 schematically illustrates an aircraft 800 with a propulsionsystem 802. The propulsion system 802 can include one or more gasturbine engines 20 of FIG. 1 and a fuel system 805 operable to providecombustible fuel to the gas turbine engines 20. The gas turbine engines20 can provide power to engine accessories, such as at least oneelectric generator 806 operable to produce an electric current. Thepropulsion system 802 can also include an electric fan propulsion motorsystem 808 powered responsive to the electric current delivered througha power distribution system 810. In the example of FIG. 9, the aircraft800 includes a pair of gas turbine engines 20 each having an electricgenerator 806. A battery system 815 may also or alternatively provideelectric current to the electric fan propulsion motor system 808. Thegas turbine engines 20 can provide thrust for the aircraft 800, rotarypower for the electric generators 806 and other accessories (notdepicted), compressed air for an environmental control system 809 tocondition a cabin 812 of the aircraft 800, and other uses. Fuel from thefuel system 805 is combusted to produce a compressor stream 807 withineach of the gas turbine engines 20.

In some embodiments, the electric fan propulsion motor system 808 can beincorporated in a tail section 814 of the aircraft 800 to provideenhanced thrust under certain operating conditions, such as take-offand/or climb. The electric fan propulsion motor system 808 may also beused to boundary layer air energization and ingestion and drag inducedby the aircraft boundary layer at the tail section 814 during operationof the aircraft 800. The electric fan propulsion motor system 808includes a propulsion motor controller 816 and an electric fanpropulsion motor 818 with a plurality of propulsion motor windings 820selectively powered responsive to electric current. The electric fanpropulsion motor 818 may also include its own fan to purge air orchilled air from a propulsion motor housing. The propulsion motorcontroller 816 is operable to control phase currents of the propulsionmotor windings 820 and thereby control a rotational velocity of theelectric fan propulsion motor 818. It will be understood that theaircraft 800 includes additional systems not depicted in FIG. 9. Inembodiments, efficiency of the electric fan propulsion motor 818 can beenhanced by an engine-driven cryogenic cooling system 900 as furtherdescribed and depicted in FIG. 10 and/or other examples as providedherein. The electric fan propulsion motor 818 may alternatively orselectively be cooled by other cooling sources, such as ambient air 817.

The electric fan propulsion motor 818 can increase power density, e.g.,thrust divided by electric power system weight, at cryogenictemperatures where air liquefies. Embodiments can provide a workingfluid flow of liquid air from a cryogenic liquid reservoir through acryogenic working fluid flow control assembly in fluid communicationwith propulsion motor windings 820 of the electric fan propulsion motor818. The working fluid flow can be controlled to pre-cool the cryogenicworking fluid flow control assembly and the propulsion motor windings820 with cooled gaseous air, while liquid air can be used to providecryogenic cooling of the propulsion motor windings 820 for higher powerdemand conditions. The working fluid flow and/or generation may bedisabled when operation of the electric fan propulsion motor 818 andother systems using the working fluid flow are not needed, such as whenthe aircraft 800 needs less than maximum thrust.

FIG. 10 depicts an engine-driven cryogenic cooling system 900 accordingto an embodiment. The engine-driven cryogenic cooling system 900includes a first air cycle machine 901 operable to produce a cooling airstream 910 based on a first engine bleed source 904. The first air cyclemachine 901 can include a plurality of components, such as a firstcompressor section 914 and a first turbine section 915 operably coupledto a gearbox 902 of the gas turbine engine 20. The gearbox 902 is anexample of a means for transferring energy from the gas turbine engine20 to a means for cryogenically cooling the aircraft 800, such as theengine-driven cryogenic cooling system 900. The gearbox 902 can beoperably coupled to a shaft of the gas turbine engine 20, such as innershaft 40 and tower shaft 903, to drive rotation of the first compressorsection 914 responsive to rotation of the tower shaft 903 and/orrotation of the first turbine section 915. The first turbine section 915can include one or more turbine wheels, such as a first turbine wheel917 and a second turbine wheel 919 operably coupled to the gearbox 902.

The first engine bleed source 904 can be a mid-compressor bleed or ahigher stage bleed of the high pressure compressor 52, for example. Ableed air flow 905 from the engine bleed source 904 can be passedthrough an air-air heat exchanger 906 to a selection valve 907, whichmay selectively direct the bleed air flow 905 to a fuel-air heatexchanger 908 or a first compressor wheel 916 of the first compressorsection 914. The fuel-air heat exchanger 908 can be interposed in fluidcommunication between the air-air heat exchanger 906 and the firstturbine wheel 917 of the first turbine section 915. The air-air heatexchanger 906 can be positioned, for example, in a duct space 80 betweena guide vane section 82 and nozzle portion 84 of the gas turbine engine20. In some embodiments, a station three bleed 909 can selectivelyprovide bleed air through a valve 940 to the air-air heat exchanger 906and can also provide engine bleed air from the high pressure compressor52 to a mixing chamber 911. The mixing chamber 911 can be in fluidcommunication with the first compressor wheel 916, the high pressurecompressor 52 of the gas turbine engine 20, and a turbine cooling airinput 912 between the high pressure compressor 52 and the combustor 56of the gas turbine engine 20. The fuel-air heat exchanger 908 isoperable to transfer heat to a fuel flow 825 from the fuel system 805,which may also pass through an airframe heat exchanger 913 beforereaching the combustor 56.

In some embodiments, an output 918 of the first turbine wheel 917 isselectively provided to a first cooling use of the aircraft 800, such asthe cabin 812 of FIG. 9. The second turbine wheel 919 can be in fluidcommunication with the first turbine wheel 917 and operable to output acooling air stream 910 that is selectively provided to a second coolinguse 942 and the second air cycle machine 920. For example, an output ofthe second turbine wheel 919 may pass through a water separator 944,with water 945 extracted and returned (e.g., as a mist spray) proximateto the air-air heat exchanger 906, and a valve 946 can control whether aportion of the cooling air stream 910 is provided with the secondcooling use 942 at a temperature below the first cooling use provided tothe cabin 812. The water separator 944 may use a condenser, such as acyclonic separator or similar structure that can swirl air over animpingement surface to cause moisture condensation, for instance, usingcentrifugal force to extract the water 945. In some embodiments, aheat-adding heat exchanger 948 can be interposed between the firstturbine wheel 917 and the second turbine wheel 919 with a control valve950 operable to control a flow between the first turbine wheel 917 andthe second turbine wheel 919. A valve 952 can selectively control a flowof an output of the first compressor wheel 916 to the heat-adding heatexchanger 948 to add heat to a flow between the first turbine wheel 917and the second turbine wheel 919 if needed.

The engine-driven cryogenic cooling system 900 also includes a secondair cycle machine 920 operable to output a chilled air stream 923 at acryogenic temperature based on a second engine bleed source 921 of thegas turbine engine 20 cooled by the cooling air stream 910 of the firstair cycle machine 901. Cryogenic temperatures can refer to temperatureswhere air, nitrogen, and/or oxygen can exist in a liquid state withrespect to pressure. The second air cycle machine 920 can include asecond compressor section 924 and a second turbine section 925 operablycoupled to the gearbox 902 of the gas turbine engine 20. Theengine-driven cryogenic cooling system 900 may also include a liquid aircollection system 930 in fluid communication with an output of thesecond air cycle machine 920. An air flow 960 from the second enginebleed source 921 can be pre-cooled through a heat exchanger system 963prior to entry into compressor wheel 926 and cool the air flow 960 afterexiting the compressor wheel 926. The second engine bleed source 921 canbe an engine source from the gas turbine engine 20 of FIG. 1, such as amid-compressor bleed, fan air, inlet air, or ambient air. The heatexchanger system 963 can include multiple stages, such as a primary heatexchanger 962 and a secondary heat exchanger 964. The air flow 960 canbe cooled through the heat exchanger system 963 after exiting thecompressor wheel 926. A cooling fan 928 can urge a heat exchangercooling flow 965 across the heat exchanger system 963, with the heatexchanger cooling flow 965 providing a cooling source 922 for theaircraft 800 of FIG. 9 after crossing the heat exchanger system 963 ordumped overboard. The heat exchanger cooling flow 965 can be or includethe cooling air stream 910 of the first air cycle machine 901. The airflow 960 can pass through additional heat exchangers 967, 968 to a waterseparator 966 in fluid communication with an output of the compressorwheel 926 and an input of the turbine wheel 927. The water separator 966is operable to spray extracted water from the air flow 960 into the heatexchanger cooling flow 965 upstream from the heat exchanger system 963.A bypass valve 976 may be included to bypass the heat exchangers 967,968 and water separator 966. An output of the turbine wheel 927 can bein fluid communication with the heat exchanger 968 which is furthercoupled to an input of the turbine wheel 929. Valves 977, 979 can beincluded to provide temperature control/anti-icing at an output of theturbine wheels 927, 929, for example, by selectively allowing a portionof the air flow 960 to be bypassed from an input of the compressor wheel926.

The liquid air collection system 930 can include a vacuum system 931configured to receive the chilled air stream 923 and maintain one ormore exit conditions of the second turbine section 925, a liquid aircondensate collection header 933, and a liquid air condensate pumpsystem 932 that urges liquid air through a feeder line 934 for storagein the cryogenic liquid reservoir 935 operably coupled to the feederline 934. In embodiments, liquid air can be stored under pressure in thecryogenic liquid reservoir 935. In some embodiments, the cryogenicliquid reservoir 935 is a cartridge that can be installed with aninitial supply of liquid air and be refilled or supplemented with liquidair produced by the engine-driven cryogenic cooling system 900. Further,the cryogenic liquid reservoir 935 can be configured to accept a refillof liquid air from an alternate source, such as a ground-based rechargeof the cryogenic liquid reservoir 935.

In embodiments, a vacuum pump valve 936 can be selectively controlled topass the chilled air stream 923 after pressurization (which may includeliquid air) through a vacuum pump vent 937 for an aircraft cooling use938 as a cooling fluid. The aircraft cooling use 938 can be, forexample, the environmental control system 809 of the aircraft 800 ofFIG. 9, cooling selected components of the gas turbine engine 20 of FIG.1, cooling a power system of the aircraft 800 such as the electricgenerators 806 and/or battery system 815, and/or other uses. A liquidair flow 981 provided from the cryogenic liquid reservoir 935 throughvalve 980 or as produced by the engine-driven cryogenic cooling system900 can be routed to one or more cryogenic uses. For example, the liquidair flow 981 can be selectively provided to the propulsion motorwindings 820 of the electric fan propulsion motor 818 of FIG. 9. Theliquid air flow 981 can also or alternatively be routed to otherelectronic loads or portions of the gas turbine engine 20. Other valveand plumbing arrangements are contemplated.

A controller 990 can interface with and control multiple elements of theengine-driven cryogenic cooling system 900, such as valve states, flowrates, pressures, temperatures, rotational state of air cycle machines901, 920, and the like. In an embodiment, the controller 990 includes amemory system 992 to store instructions that are executed by aprocessing system 994 of the controller 990. The executable instructionsmay be stored or organized in any manner and at any level ofabstraction, such as in connection with a controlling and/or monitoringoperation of the engine-driven cryogenic cooling system 900. Theprocessing system 994 can include one or more processors that can be anytype of central processing unit (CPU), including a microprocessor, adigital signal processor (DSP), a microcontroller, an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), or the like. Also, in embodiments, the memory system 992 mayinclude random access memory (RAM), read only memory (ROM), or otherelectronic, optical, magnetic, or any other computer readable mediumonto which is stored data and control algorithms in a non-transitoryform.

Although one example of the engine-driven cryogenic cooler system 900 isdepicted in the example of FIG. 10, it will be understood thatadditional elements and modifications are contemplated, such as only oneturbine wheel in either or both of the air cycle machines 901, 920,recirculation paths, pumps, intermediate taps, relief valves, and/orother such elements known in the art.

FIG. 11 is a flow chart illustrating a method 1000 of engine-drivencryogenic cooling fluid generation in accordance with an embodiment. Themethod 1000 of FIG. 11 is described in reference to FIGS. 1-11 and maybe performed with an alternate order and include additional steps. Themethod 1000 can be performed, for example, by the engine-drivencryogenic cooling system 900 of FIG. 10.

At block 1002, rotation of a plurality of components of a first aircycle machine 901 is driven through a gearbox 902 operably coupled to ashaft (e.g., a tower shaft 903) of a gas turbine engine 20 to produce acooling air stream 910 based on a first engine bleed source 904 of thegas turbine engine 20.

A bleed air flow 905 can be selectively passed from the engine bleedsource 904 through an air-air heat exchanger 906 interposed in fluidcommunication between the first engine bleed source 904 and the firstcompressor wheel 916. The bleed air flow 905 can be selectively passedfrom the air-air heat exchanger 906 to the through a fuel-air heatexchanger 908 interposed in fluid communication between the air-air heatexchanger 906 and a first turbine wheel 917 of the first turbine section915.

An output 918 of the first turbine wheel 917 can be selectively providedto a first cooling use of the aircraft 800, such as the cabin 812. Thecooling air stream 910 can be selectively provided from a second turbinewheel 919 in fluid communication with the first turbine wheel 917 to asecond cooling use 942 and the second air cycle machine 920.

A selection valve 907 interposed in fluid communication between theair-air heat exchanger 906 and the fuel-air heat exchanger 908 isoperable to direct an output of the air-air heat exchanger 906 to thefirst compressor wheel 916 or the fuel-air heat exchanger 908. Aplurality of flows from the first compressor wheel 916 and a highpressure compressor 52 of the gas turbine engine 20 can be mixed toprovide a turbine cooling air input 912 between the high pressurecompressor 52 and the combustor 56 of the gas turbine engine 20.

A heat exchanger system 963 can precool an air flow 960 from the secondengine bleed source 921 prior to entry into the second compressorsection 924 of the second air cycle machine 920. The heat exchangersystem 963 can cool the air flow 960 after exiting the second compressorsection 924. A cooling fan 928 can urge a heat exchanger cooling flow965 across the heat exchanger system 963, where the heat exchangercooling flow 965 includes the cooling air stream 910 of the first aircycle machine 901. The heat exchanger cooling flow 965 can be providedas a cooling source 922 for the aircraft 800 after crossing the heatexchanger system 963.

At block 1004, a chilled air stream 923 is output at a cryogenictemperature from the second air cycle machine 920 based on the secondengine bleed source 921 cooled by the cooling air stream 910 of thefirst air cycle machine 901. At block 1006, the chilled air stream 923is condensed into liquid air for an aircraft use using a means forcondensing the chilled air stream 923, such as the liquid air collectionsystem 930. The chilled air stream 923 can be received at a vacuumsystem 931 to maintain one or more exit conditions (e.g., pressure) ofthe second turbine section 925. A vacuum pump valve 936 is operablycoupled to the vacuum system 931 and can selectively release the chilledair stream 923 for an aircraft cooling use 938 as a cooling fluid. Theliquid air collected in the liquid air condensate collection header 933can be urged by a liquid air condensate pump system 932 through a feederline 934. Liquid air may be collected in a cryogenic liquid reservoir935 for the aircraft use, such as cooling one or more components of theaircraft 800.

FIG. 12 depicts a cryogenic cooling system 1200 according to anembodiment. The cryogenic cooling system 1200 can include one or moreliquid air storage vessel 1202 and/or a cryogenic cooler 1242. A meansfor selectively releasing a cooling fluid flow can include the liquidair storage vessel 1202 and cryogenic cooler 1242 as examples of aliquid air source 1201, where liquid air can be generated for immediateconsumption by the cryogenic cooler 1242 and/or released from the liquidair storage vessel 1202. The liquid air storage vessel 1202 isconfigured to selectively release a cooling fluid flow 1206 produced ata cryogenic temperature. Cryogenic temperatures can refer totemperatures where air, nitrogen, and/or oxygen can exist in a liquidstate with respect to pressure. In some embodiments, the liquid airstorage vessel 1202 is absent and liquid air produced by the cryogeniccooler 1242 is allowed to flow as cooling fluid flow 1206 directly to aplumbing system 1204 in fluid communication with the liquid air source1201 for cooling one or more components of the gas turbine engine 20.Although referred to as a liquid air storage vessel, the liquid airstorage vessel 1202 can, in some embodiments, store liquid nitrogen,liquid oxygen, and/or a combination thereof, such as a mixture of liquidoxygen and gaseous nitrogen. In other embodiments, the cryogenic cooler1242 is absent, and liquid air released by the liquid air storage vessel1202 selectively flows as cooling fluid flow 1206 to the plumbing system1204. In a further embodiment, the liquid air storage vessel 1202 isrecharged by the cryogenic cooler 1242. The plumbing system 1204 caninclude tubing that is insulated and/or includes multiple walls toreduce heat transfer. Further, the plumbing system 1204 can be routedthrough one or more components of the gas turbine engine 20 and may beinternal and/or external to portions of the gas turbine engine 20.

The cryogenic cooling system 1200 is operable to control a flow rate ofthe cooling fluid flow 1206 through the plumbing system 1204 to one ormore components 1208A, 1208B of the gas turbine engine 20 of FIG. 1. Inthe example of FIG. 12, a pump 1210 is operable to urge the coolingfluid flow 1206 to the control a flow rate of the cooling fluid flow1206 through the plumbing system 1204 to the one or more components1208A, 1208B. The pump 1210 can be a liquid pump that efficiently pumpsthe cooling fluid flow 1206 in a liquid or mixed state. For instance,depending upon the cryogenic temperature and corresponding pressure, thecooling fluid flow 1206 may be any of a combination of liquid, gas, andsupercritical fluid as the cooling fluid flow 1206 flows through theplumbing system 1204. The cooling fluid flow 1206 can absorb heat at asit passes through the plumbing system 1204, resulting in increasedcompression/pressure and possible state changes. As one example, thecooling fluid flow 1206 may reach a pressure of 60 atmospheres or higherdue to heat absorption through a case and/or plumbing system 1204 of thegas turbine engine 20. The release of the cooling fluid flow 1206 can bemodulated at a desired duty cycle to conserve liquid air produced and/orstored in the cryogenic cooling system 1200.

The cooling fluid flow 1206 can be liquid air released from the liquidair storage vessel 1202, cool gaseous air, and/or a mix of liquid andgaseous air. For example, the liquid air can be stored under pressure inthe liquid air storage vessel 1202 and may change to a gaseous stateupon entering a warmer environment of the plumbing system 1204. Further,the flow coursing through entire system to an exit point can experiencea continuously lowering pressure causing liquid air to boil into gaseousair in the cooling fluid flow 1206.

A combination of valves can be used to control the flow rate of thecooling fluid flow 1206. For example, a control valve 1212 is operableto control the flow rate of the cooling fluid flow 1206 into theplumbing system 1204. One or more control valves, such as valve 1214,can be used to modify a flow rate between the one or more components1208A, 1208B.

In embodiments, the liquid air storage vessel 1202 can include one ormore removable/rechargeable containers or can be integrated within thecryogenic cooling system 1200. The liquid air storage vessel 1202 canhave a 5000 pounds-per-square-inch (PSI) pressure rating. In the exampleof FIG. 12, the liquid air storage vessel 1202 is coupled in fluidcommunication with a feeder line 1240. In some embodiments, the feederline 1240 enables an external source to recharge the liquid air storagevessel 1202 with liquid air. In some embodiments, the cryogenic coolingsystem 1200 includes at least one cryogenic cooler 1242 operable togenerate and produce liquid air for immediate use and/or storage in theliquid air storage vessel 1202 during operation of the gas turbineengine 20 of FIG. 1. For example, the cryogenic cooler 1242 can includeone or more air cycle machines 1244 operable to compress, chill, expand,pump, and condense an air flow to produce liquid air for storage in theliquid air storage vessel 1202 and/or immediate use.

As one example, the cryogenic cooler 1242 can include a heat exchangersystem 1246 operable to receive a cooling air intake 1248. A compressor1250 can receive bleed air 1252 from the gas turbine engine 20 of FIG. 1as an air flow. Compressed air 1254 output by the compressor 1250 canpass through the heat exchanger system 1246 to at least one turbine 1256as a cooled flow 1258 to a vacuum system 1260 and a liquid aircondensate pump system 1262 that urges liquid air through the feederline 1240 for storage in the liquid air storage vessel 1202. Thecompressor 1250 and the at least one turbine 1256 may be mechanicallylinked by a coupling 1264, such as a shaft. In some embodiments, thecompressor 1250 and the at least one turbine 1256 are not physicallycoupled. The compressor 1250 can be driven mechanically by the gasturbine engine 20 of FIG. 1 and/or electrically using an electric motor(not depicted). Although one example of the cryogenic cooler 1242 isdepicted in the example of FIG. 12, it will be understood thatadditional elements and modifications are contemplated, such as two ormore turbine wheels, recirculation paths, water separation, one or morefan sections, intermediate taps, relief valves, and/or other suchelements known in the art.

A controller 1290 can interface with and control multiple elements ofthe cryogenic cooling system 1200, such as valve states, flow rates,pressures, temperatures, rotational state of one or more air cyclemachines 1244, and the like. In an embodiment, the controller 1290includes a memory system 1292 to store instructions that are executed bya processing system 1294 of the controller 1290. The executableinstructions may be stored or organized in any manner and at any levelof abstraction, such as in connection with a controlling and/ormonitoring operation of the cryogenic cooling system 1200. Theprocessing system 1294 can include one or more processors that can beany type of central processing unit (CPU), including a microprocessor, adigital signal processor (DSP), a microcontroller, an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), or the like. Also, in embodiments, the memory system 1292 mayinclude random access memory (RAM), read only memory (ROM), or otherelectronic, optical, magnetic, or any other computer readable mediumonto which is stored data and control algorithms in a non-transitoryform.

FIG. 13 depicts a plot 1300 of relative internal temperature changes vs.time for a various flight phases in accordance with an embodiment. Theplot 1300 can be established for nominal conditions of the gas turbineengine 20 of FIG. 1 and further augmented based on one or more operatingparameters of the gas turbine engine 20. For example, by monitoringpressures and temperatures of the gas turbine engine 20, it can bedetermined how closely a particular instance of the gas turbine engine20 follows the plot 1300, and the use of plot 1300 for control actionscan be augmented based on variations observed in one or more operatingparameters of the gas turbine engine 20.

In the example of FIG. 13, an internal temperature of the gas turbineengine 20 is relatively low at idle 1302 and climbs rapidly at takeoffpower 1304. At climb 1306, climb to cruise 1308, and subsequent cruisestates 1310, 1312, 1314, the internal temperature of the gas turbineengine 20 may gradually reduce as the power demand is reduced and thegas turbine engine 20 is surrounded by cooler ambient air at altitude.The internal temperature of the gas turbine engine 20 can be furtherreduced at decent 1316. A temporary spike in the internal temperature ofthe gas turbine engine 20 may be experienced during a thrust reverse1318 operation prior to shut down.

FIG. 14 is a schematic illustration of a gas turbine engine component1400 in accordance with an embodiment. The gas turbine engine component1400 is an example of a component within the gas turbine engine 20 ofFIG. 1, such as a vane, where a feeder tube 1402 is operable to receivethe cooling fluid flow 1206 of FIG. 12. For example, the gas turbineengine component 1400 can be one of the components 1208A, 1208B of FIG.12 in the compressor section 24 or the turbine section 28 of the gasturbine engine 20. A body 1404 of the gas turbine engine component 1400can include a plurality of lines 1406 to transfer a portion 1408 of thecooling fluid flow 1206 to a desired location within the gas turbineengine 20. The lines 1406 can be hollow and ceramic lined to insulatethe cooling fluid flow 1206.

FIG. 15 is a schematic illustration of portions of the gas turbineengine 20 configured to receive the cooling fluid flow 1206 of FIG. 12in accordance with an embodiment. The cooling fluid flow 1206 can besent to one or more locations of the gas turbine engine 20 to enhancecooling effects and increase engine efficiency. Example locations asdepicted in FIG. 15 can include a rear compressor rim cavity 1502, arear high pressure compressor flow from the front 1504 of a diffusercase, a location at or in proximity to a tangential on-board injector(TOBI) flow such as a TOBI flow proximate to a first disk rim cavity1506 routed from the diffuser case, a front side plate and/or outercavity area 1508 cooling flow to mitigate recirculation of gas path air,a first blade cooling flow 1510 from the TOBI flow, a front cavity 1512of the turbine section 28, a front low pressure turbine transition ductcooling location 1514, and other such locations.

FIG. 16 is a schematic illustration of portions of the gas turbineengine 20 configured to receive the cooling fluid flow 1206 of FIG. 12.One or more buffer cooling locations 1602 are configured to receivechilled air delivered from the cooling fluid flow 1206 of FIG. 12. Thebuffer cooling locations 1602 can be plenums established relative to astationary outer seal 1604, a rotating outer seal land 1606, astationary inner seal 1608, and a rotating inner seal 1610.

FIG. 17 is a schematic illustration of portions of gas turbine engine 20configured to receive the cooling fluid flow 1206 of FIG. 12 inaccordance with an embodiment. In the example of FIG. 17, a rear highpressure compressor flow at the compressor section 24 can be deliveredfrom tubes 1702 in front of a diffuser case. The rear high pressurecompressor flow can pass through holes and/or slots 1704 toward a drum.One or more covers 1706 can be incorporated to prevent the cooling fluidflow 1206 from escaping. Other flow control options are contemplated.

FIG. 18 is a flow chart illustrating a method 1800 of cooling componentsof a gas turbine engine in accordance with an embodiment. The method1800 of FIG. 18 is described in reference to FIGS. 1-18 and may beperformed with an alternate order and include additional steps. Themethod 1800 can be performed, for example, by the cryogenic coolingsystem 1200 of FIG. 12.

At block 1802, controller 1290 determines a flight phase of an aircraft.For example, the flight phase can be determined in reference to the plot1300. At block 1804, controller 1290 determines an operating parameterof a gas turbine engine 20 of the aircraft. The operating parameter canbe one or more of a pressure and/or temperature within the gas turbineengine 20. At block 1806, liquid air is selectively released from aliquid air source 1201 to a plumbing system 1204 configured to route acooling fluid flow 1206 from the liquid air source 1201 to one or moreof a compressor section 24 and a turbine section 28 of the gas turbineengine 20 based on either or both of the flight phase and the operatingparameter of the gas turbine engine 20. The plumbing system 1204 can berouted to deliver the cooling fluid flow 1206 to one or more of: a highcompressor flow, a turbine blade, and a turbine transition duct.

FIG. 19 depicts a cryogenic cooling system 2200 according to anembodiment. The cryogenic cooling system 2200 includes a first air cyclemachine 2201 operable to output a cooling air stream 2210 based on afirst air source 2204, a second air cycle machine 2220 operable tooutput a chilled air stream 2223 at a cryogenic temperature based on asecond air source 2221 cooled by the cooling air stream 2210 of thefirst air cycle machine 2201, a liquid air collection system 2230 influid communication with an output of the second air cycle machine 2220,and a cryogenic air separator 2240 in fluid communication with theliquid air collection system 2230. The cryogenic air separator 2240 isoperable to separate gaseous nitrogen 2242 and liquid oxygen 2244 fromliquid air collected by the liquid air collection system 2230. Thegaseous nitrogen 2242 can be used for various systems of the aircraft800, such as inerting of the fuel system 805 of FIG. 9. The liquidoxygen 2244 can also be used for various systems of the aircraft 800,such as supplying liquid oxygen 2244 to the cabin 812 of the aircraft800 and/or in a compressor stream 807 of a gas turbine engine 20 toenhance combustion efficiency.

In the example of FIG. 19, the first air cycle machine 2201 includes acompressor section 2214 and a turbine section 2215 (referred to as firstsections), and the second air cycle machine 2220 includes a compressorsection 2224 and a turbine section 2225 (referred to as secondsections). The compressor section 2214 can include a compressor wheel2216 operably coupled to a turbine wheel 2217 of the turbine section2215 and a fan 2218. The turbine section 2215 can also include anotherturbine wheel 2219 operatively coupled to the turbine wheel 2217.Similarly, the compressor section 2224 can include a compressor wheel2226 operably coupled to a turbine wheel 2217 of the turbine section2225 and a fan 2228. The turbine section 2225 can also include anotherturbine wheel 2229 operatively coupled to the turbine wheel 2227.

A first air flow 2250 from the first air source 2204 can be urgedthrough a heat exchanger system 2203 prior to entry into the compressorwheel 2216 to pre-cool the first air flow 2250. The first air source2204 can be an engine bleed source from the gas turbine engines 20 ofFIG. 1, such as a high stage bleed. The heat exchanger system 2203 caninclude multiple stages, such as a primary heat exchanger 2252 and asecondary heat exchanger 2254. The first air flow 2250 can be cooledthrough the heat exchanger system 2203 after exiting the compressorwheel 2216. The fan 2218 can urge a heat exchanger cooling flow 2202across the heat exchanger system 2203, with heated air 2205 dumpedoverboard. The first air flow 2250 can pass through additional heatexchangers 2207, 2208 to a water separator 2206 in fluid communicationwith an output of the first compressor wheel 2216 and an input of thefirst turbine wheel 2217. The water separator 2206 is operable to sprayextracted water from the first air flow 2250 into the first heatexchanger cooling flow 2202 upstream from the heat exchanger system2203. A bypass valve 2256 may be included to bypass the heat exchangers2207, 2208 and water separator 2206. An output of the turbine wheel 2217can be in fluid communication with the heat exchanger 2208 which isfurther coupled to an input of the turbine wheel 2219. Valves 2257, 2259can be included to provide temperature control/anti-icing at outputs ofthe turbine wheels 2217, 2219 respectively, for example, by selectivelyallowing a portion of the first air flow 2250 to be bypassed from aninput of the compressor wheel 2216.

Similarly, a second air flow 2260 from the second air source 2221 can bepre-cooled through a heat exchanger system 2263 prior to entry into thecompressor wheel 2226 and cool the second air flow 2260 after exitingthe second compressor wheel 2226. The second air source 2221 can be anengine source from the gas turbine engines 20 of FIG. 1, such as amid-compressor bleed, fan air, inlet air, or ambient air. The heatexchanger system 2263 can include multiple stages, such as a primaryheat exchanger 2262 and a secondary heat exchanger 2264. The second airflow 2260 can be cooled through the heat exchanger system 2263 afterexiting the compressor wheel 2226. The fan 2228 can urge a heatexchanger cooling flow 2265 across the heat exchanger system 2263, withcool air 2222 used onboard the aircraft 800 of FIG. 9 (e.g., byenvironmental control system 809 of FIG. 9) or dumped overboard. Thesecond heat exchanger cooling flow 2265 can be or include the coolingair stream 2210 of the first air cycle machine 2201. The second air flow2260 can pass through additional heat exchangers 2267, 2268 to a waterseparator 2266 in fluid communication with an output of the compressorwheel 2226 and an input of the turbine wheel 2227. The water separator2266 is operable to spray extracted water from the second air flow 2260into the heat exchanger cooling flow 2265 upstream from the heatexchanger system 2263. A bypass valve 2276 may be included to bypass theheat exchangers 2267, 2268 and water separator 2266. An output of theturbine wheel 2227 can be in fluid communication with the heat exchanger2268 which is further coupled to an input of the turbine wheel 2229.Valve 2277 can be included to provide temperature control/anti-icing atan output of the turbine wheel 2227, for example, by selectivelyallowing a portion of the second air flow 2260 to be bypassed from aninput of the compressor wheel 2226.

The liquid air collection system 2230 can include a vacuum system 2231,a liquid air condensate collection header 2233, and a liquid aircondensate pump system 2232 that urges liquid air through a feeder line2234 for storage in the cryogenic liquid reservoir 2235 operably coupledto the feeder line 2234. In embodiments, liquid air can be stored underpressure in the cryogenic liquid reservoir 2235. In some embodiments,the cryogenic liquid reservoir 2235 is a cartridge that can be installedwith an initial supply of liquid air and be refilled or supplementedwith liquid air produced by the cryogenic cooling system 2200. Further,the cryogenic liquid reservoir 2235 can be configured to accept a refillof liquid air from an alternate source, such as a ground-based rechargeof the cryogenic liquid reservoir 2235.

In embodiments, a valve 2236 can be selectively controlled to pass thechilled air stream 2223 after pressurization (which may include liquidair) through a vacuum pump vent 2237 for an aircraft cooling use 2238 asa cooling fluid. The aircraft cooling use 2238 can be, for example, theenvironmental control system 809 of the aircraft 800 of FIG. 9, coolingselected components of the gas turbine engines 20 of FIG. 1, cooling apower system of the aircraft 800 such as the electric generators 806and/or battery system 815, and/or other uses. A liquid air flow 2281provided from the cryogenic liquid reservoir 2235 through valve 2280 oras produced by the cryogenic cooling system 2200 can be routed to one ormore cryogenic uses. For example, a valve 2282 may control the liquidair flow 2281 to a cryogenic working fluid flow control assembly 2284 influid communication with the propulsion motor windings 820 of theelectric fan propulsion motor 818 of FIG. 9. The liquid air flow 2281can also or alternatively be routed to other electronic loads. Further,the valve 2282 may also control the liquid air flow 2281 to thecryogenic air separator 2240. Other valve and plumbing arrangements arecontemplated.

A controller 2290 can interface with and control multiple elements ofthe cryogenic cooling system 2200, such as valve states, flow rates,pressures, temperatures, rotational state of air cycle machines 2201,2220, and the like. In an embodiment, the controller 2290 includes amemory system 2292 to store instructions that are executed by aprocessing system 2294 of the controller 2290. The executableinstructions may be stored or organized in any manner and at any levelof abstraction, such as in connection with a controlling and/ormonitoring operation of the cryogenic cooling system 2200. Theprocessing system 2294 can include one or more processors that can beany type of central processing unit (CPU), including a microprocessor, adigital signal processor (DSP), a microcontroller, an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), or the like. Also, in embodiments, the memory system 2292 mayinclude random access memory (RAM), read only memory (ROM), or otherelectronic, optical, magnetic, or any other computer readable mediumonto which is stored data and control algorithms in a non-transitoryform.

Although one example of the cryogenic cooler system 2200 is depicted inthe examples of FIG. 19, it will be understood that additional elementsand modifications are contemplated, such as only one turbine wheel ineither or both of the air cycle machines 2201, 2220, recirculationpaths, pumps, intermediate taps, relief valves, and/or other suchelements known in the art.

FIG. 20 depicts a cryogenic air separator 2300 as one example of thecryogenic air separator 2240 of FIG. 19 in accordance with anembodiment. The cryogenic air separator 2300 includes a separationvessel 2302 with at least one liquid air input port 2304, at least onegaseous nitrogen output port 2306, and at least one liquid oxygen outputport 2308. The liquid air input port 2304 is operable to receive theliquid air flow 2281 from the liquid air collection system 2230 of FIG.19. The temperature of the liquid air flow 2281 can be below the boilingpoints of nitrogen, oxygen, and other constituents of air upon reachingliquid air input port 2304. The separation vessel 2302 can be sized,located, and otherwise temperature controlled to allow nitrogen to boiloff from the liquid air flow 2281 through the gaseous nitrogen outputport 2306 as gaseous nitrogen 2242 while liquid oxygen 2244 remains andflows out of the liquid oxygen output port 2308. For instance, inreference to an example at ambient atmospheric pressure, as the liquidair flow 2281 is warmed from about −200 degrees C., nitrogen would boiloff at temperatures at or above −195.8 degrees C., leaving liquid oxygenor an oxygen-rich liquid if the temperature remains below −183 degreesC., for example. The separation in the cryogenic air separator 2300 istemperature-based in that differences in boiling points of nitrogen andoxygen allow for nitrogen to transition into a gaseous state whileoxygen (and potentially argon) remains liquefied while the temperatureof the liquid air flow 2281 rises upon entry into the separation vessel2302. The pressure of the liquid air flow 2281 can be set/adjusted(e.g., by controller 2290 of FIG. 19) to match the separationperformance properties of the cryogenic air separator 2300, asliquid/gas state is a function of pressure and temperature. Although theexample of FIG. 20 includes a single separation vessel 2302, it will beunderstood that other configurations can be implemented, such as aseries of separation vessels 2302.

FIG. 21 depicts a cryogenic air separator 2400 as another example of thecryogenic air separator 2240 of FIG. 19 in accordance with anembodiment. The cryogenic air separator 2400 includes a separationvessel 2402 with at least one liquid air input port 2404, at least onegaseous nitrogen output port 2406, at least one liquid oxygen outputport 2408, and a stagnation plate 2410. The cryogenic air separator 2400is referred to as a stagnation plate-based separator, in that the liquidair flow 2281 received at the liquid air input port 2404 from the liquidair collection system 2230 of FIG. 19 strikes the stagnation plate 2410to enhance separation of the gaseous nitrogen 2242 and the liquid oxygen2244. The stagnation plate 2410 can include variations in curvature andflow paths, resulting in trapping regions that alter the flow velocityand pressure of the liquid air flow 2281. In regions where the flowvelocity and pressure change, a partial state change can occur where thegaseous nitrogen 2242 is released (boiled) from the liquid air flow 2281and output from the gaseous nitrogen output port 2406, while theremaining liquid retains oxygen (and potentially argon) in the liquidoxygen 2244 is output from the liquid oxygen output port 2408. Althoughone example configuration is depicted in FIG. 21, it will be understoodthat various configurations of the stagnation plate 2410 can beimplemented in embodiments.

FIG. 22 depicts a cryogenic air separator 2500 as another example of thecryogenic air separator 2240 of FIG. 19 in accordance with anembodiment. The cryogenic air separator 2500 includes a separationvessel 2502 with at least one liquid air input port 2504, at least onegaseous nitrogen output port 2506, at least one liquid oxygen outputport 2508, and a magnetic field generator 2510. The cryogenic airseparator 2500 is referred to as a magnetic-based separator. The liquidair flow 2281 received at the liquid air input port 2504 from the liquidair collection system 2230 of FIG. 19 may initially separate due to thepressure/temperature change within the separation vessel 2502 anddifferences in the boiling points of nitrogen and oxygen. The controller2290 of FIG. 19 may apply a magnetic field by controlling a flow ofelectric current through the magnetic field generator 2510 (e.g., coilsof wires). The magnetic field generator 2510 can be located proximate tothe oxygen output port 2508 to take advantage of the paramagnetism ofthe liquid oxygen 2244 to attract/urge the liquid oxygen 2244 toward theliquid oxygen output port 2508 while the gaseous nitrogen 2242 rises tothe gaseous nitrogen output port 2506. Although one exampleconfiguration is depicted in FIG. 22, it will be understood that variousconfigurations of the magnetic field generator 2510 are contemplated.Further embodiments can combine elements of the cryogenic air separators2300-2500 of FIGS. 20-22.

FIG. 23 is a flow chart illustrating a method 2600 of propulsion systemcooling control in accordance with an embodiment. The method 2600 ofFIG. 23 is described in reference to FIGS. 1-23 and may be performedwith an alternate order and include additional steps. The method 2600can be performed, for example, by the cryogenic cooling system 2200 ofFIG. 19.

At block 2602, a cooling air stream 2210 is output from a first aircycle machine 2201 based on a first air source 2204. At block 2604, achilled air stream 2223 is output at a cryogenic temperature from asecond air cycle machine 2220 based on a second air source 2221 cooledby the cooling air stream 2210 of the first air cycle machine 2201. Atblock 2606, liquid air is collected in a liquid air collection system2230 from an output of the second air cycle machine 2220. At block 2608,the cryogenic air separator 2240 can be used to separate gaseousnitrogen 2242 and liquid oxygen 2244 from the liquid air collected bythe liquid air collection system 2230. The cryogenic air separator 2240can separate the gaseous nitrogen 2242 and liquid oxygen 2244 based onone or more of: a temperature-based separator 2300, a stagnationplate-based separator 2400, and a magnetic-based separator 2500.

In embodiments, the gaseous nitrogen 2242 can be supplied to a fuelsystem 805 of an aircraft 800. The gaseous nitrogen 2242 can be used tobe used to sparge the fuel and remove oxygen, which may eliminate theneed for a fuel deoxygenation system based on membranes. The liquidoxygen 2244 can be supplied to one or more of: a cabin 812 of theaircraft 800 and a compressor stream 807 of a gas turbine engine 20 ofthe aircraft 800. The liquid air can be supplied as a cooling fluid toone or more of: an electric fan propulsion motor 818 of the aircraft800, an environmental control system 809 of the aircraft 800, a powersystem (e.g., electric generators 806, power distribution system 810,and/or battery system 815) of the aircraft 800, and a gas turbine engine804 of the aircraft 800. Using the gaseous nitrogen 2242 and liquidoxygen 2244 produced by the cryogenic cooling system 2200 can reduce thestorage and/or alternate generation needs of nitrogen and oxygen on theaircraft 800. Further, injection of liquid or cooled oxygen into thecompressor stream 807 can provide intercooling with enhanced oxygenconcentration for higher combustion temperatures without requiringadditional compression and the associated parasitic losses of additionalgas volume. This may further enhance thermodynamic efficiency in aBrayton cycle machine. For example, given that oxygen is a minorityconstituent in air by ⅕, just 10% cooled cooling air can result in up toa 50% increase in oxygen available for combustion. Further, oxygeninjection into the compressor stream 807 can result in acceleration timereductions by providing an additional oxidizer independent of theangular moment of inertia associated with spooling up the rotatingcompression machinery of the gas turbine engines 20.

A propulsion system that includes at least one electric fan propulsionmotor can increase power density, e.g., thrust divided by electric powersystem weight, at cryogenic temperatures where air liquefies.Embodiments control a working fluid flow of liquid air from a cryogenicliquid reservoir through a cryogenic working fluid flow control assemblyin fluid communication with propulsion motor windings of an electric fanpropulsion motor. The working fluid flow can be controlled to pre-coolthe cryogenic working fluid flow control assembly and the propulsionmotor windings with cooled gaseous air, while liquid air can be used toprovide cryogenic cooling of the propulsion motor windings for higherpower demand conditions. Further the embodiments of the disclosed systemfacilitate the rapid transition of the electric fan propulsion motorfrom low power to maximum power which assists an aircraft incircumstances including the transition from idle to takeoff withoutdamaging the propulsion motor. The working fluid flow and/or generationmay be disabled when operation of the electric fan propulsion motor isnot needed, such as when the aircraft needs less than maximum thrust.

FIG. 24 depicts a cryogenic cooling system 3200 according to anembodiment. The cryogenic cooling system 3200 can include one or morecryogenic liquid reservoir 3202 and a cryogenic working fluid flowcontrol assembly 3204 in fluid communication with the propulsion motorwindings 820 of the electric fan propulsion motor 818. The cryogeniccooling system 3200 is a means for controlling a flow rate of a workingfluid 3206 through the cryogenic working fluid flow control assembly3204 to the propulsion motor winding 820. The cryogenic cooling system3200 is operable to control a flow rate of a working fluid 3206 throughthe cryogenic working fluid flow control assembly 3204 to the propulsionmotor windings 820. The cryogenic cooling system 3200 can include a pump3205 operable to urge the working fluid 3206 into the cryogenic workingfluid flow control assembly 3204 and maintain a desired pressure. Theworking fluid 3206 can be liquid air released from the cryogenic liquidreservoir 3202, cool gaseous air, and/or a mix of liquid and gaseousair. For example, the liquid air can be stored under pressure in thecryogenic liquid reservoir 3202 and may change to a gaseous state uponentering a warmer environment of the cryogenic working fluid flowcontrol assembly 3204. Further the flow coursing through entire systemfrom the cryogenic liquid reservoir 3202 to an exit will see acontinuously lowering pressure causing the liquid air to boil intogaseous air, and this change of state largely occurring in certainpassages in the electric fan propulsion motor 818 can be advantageous.As the cryogenic working fluid flow control assembly 3204 is cooled, theworking fluid 3206 may pass through a primary cooling line 3208 andreach a manifold 3210 of the cryogenic working fluid flow controlassembly 3204 as liquid air to cryogenically chill the propulsion motorwindings 820. The manifold 3210 can include multiple taps 3212 to flowthe working fluid 3206 into close proximity with the propulsion motorwindings 820.

In a transient situation of an aircraft at the beginning of the runway,it is desirable to have all engines at takeoff power within about sixseconds. In that circumstance the electric propulsion motor controller816 may regulate the rate of change of electricity flow to the electricfan propulsion motor 818, but this rate of change to achieve fulltakeoff power is by definition very rapid. Cooling system mass flow rateand temperatures presented to the electric fan propulsion motor 818 canalso be about as rapid to protect the electric fan propulsion motor 818from damage or deterioration over time.

A combination of valves can be used to control the flow rate of theworking fluid 3206. For example, a main flow control valve 3214 isoperable to control the flow rate of the working fluid 3206 through aprimary cooling line 3208 of the cryogenic working fluid flow controlassembly 3204 to the propulsion motor windings 820. In some embodiments,the main flow control valve 3214 is a variable position valve operableto transition between a closed position, a partially opened position tosupply a pre-cooling flow, and a fully opened position to supply a fullcooling flow. The terms “full” and “fully” refer to a sufficient levelto meet a demand and need not be the maximum level attainable. In otherembodiments, the main flow control valve 3214 is a discrete on/off valvethat can be commanded to either a fully opened or a fully closedposition. The cryogenic working fluid flow control assembly 3204 canalso include a bypass cooling line 3216 and a bypass flow control valve3218 configured to selectively provide a pre-cooling flow as a bypasscooling flow around the main flow control valve 3214. The cryogeniccooling system 3200 of FIG. 24 is an example of a system that includesthe bypass cooling line 3216 and bypass flow control valve 3218, while acryogenic cooling system 3300 of FIG. 25 includes the same elements asthe cryogenic cooling system 3200 of FIG. 24 but excludes the bypasscooling line 3216 and bypass flow control valve 3218. Thus, the mainflow control valve 3214 of the cryogenic cooling system 3300 of FIG. 25can be implemented as a variable position valve. In some embodiments, anon-cryogenic cooling flow 3215 can be supplied to the propulsion motorwindings 820 of the electric fan propulsion motor 818 through a checkvalve 3217 in fluid communication with the manifold 3210. Thenon-cryogenic cooling flow 3215 can be provided by a cooling source3219, such as ambient air 817, air from the environmental control system809 of FIG. 9, or another source (not depicted).

With continued reference to FIGS. 24 and 25, a purge valve 3220 can becoupled to the manifold 3210 proximate to a housing 3222 of the electricfan propulsion motor 818. The purge valve 3220 can be controlled torelease gaseous air that has accumulated in the cryogenic working fluidflow control assembly 3204 as part of a process of supplying apre-cooling flow of the working fluid 3206 from the cryogenic liquidreservoir 3202 through the cryogenic working fluid flow control assembly3204 to the propulsion motor windings 820.

The cryogenic cooling system 3200 and/or cryogenic cooling system 3300can also include a controller 3224. The controller 3224 can interfacewith the main flow control valve 3214, the bypass flow control valve3218, and the purge valve 3220 through an input/output interface 3226.The controller 3224 can also interface with one or more sensors, such asone or more temperature sensors 3228 and/or one or more pressure sensors3230. Temperature sensors 3228 can be located proximate to the purgevalve 3220, proximate to one or more taps 3212 of the manifold 3210,and/or at other locations to determine a temperature within the manifold3210, an exit temperature, or other temperatures. Although depictedproximate to the housing 3222 and manifold 3210, the pressure sensors3230 can be located remotely from the housing 3222 and manifold 3210 ifpressure taps and ducting are used. The controller 3224 can be combinedwith the propulsion motor controller 816 of FIG. 9, or the controller3224 may be separate from the propulsion motor controller 816.

In embodiments, the controller 3224 is operable to control changes inthe flow rate of the working fluid 3206 and timing of opening andclosing the purge valve 3220 based on temperature data from the one ormore temperature sensors 3228. The controller 3224 may alternatively oradditionally be operable to control changes in the flow rate of theworking fluid 3206 and timing of opening and closing the purge valve3220 based on pressure data from the one or more pressure sensors 3230.In some embodiments, a speed of rotation of a rotor 3232 of the electricfan propulsion motor 818 is limited responsive to confirming whether theworking fluid 3206 is reaching the propulsion motor windings 820 in aliquid state. Temperature and/or pressure data from the temperaturesensors 3228 and pressure sensors 3230 can be used to confirm whetherthe working fluid 3206 is in a liquid state. The propulsion motorcontroller 816 of FIG. 9 can set or limit the electric current providedto the propulsion motor windings 820 based on determining whether theworking fluid 3206 is in the liquid state at the propulsion motorwindings 820. When implemented as separate controllers, a communicationinterface 3234 of the controller 3224 can send a limit signal, a liquidstate confirmation signal, and/or other signals to the propulsion motorcontroller 816 of FIG. 9.

In an embodiment, the controller 3224 also includes a memory system 3236to store instructions that are executed by a processing system 3238 ofthe controller 3224. The executable instructions may be stored ororganized in any manner and at any level of abstraction, such as inconnection with a controlling and/or monitoring operation of thecryogenic cooling system 3200, 3300. The processing system 3238 caninclude one or more processors that can be any type of centralprocessing unit (CPU), including a microprocessor, a digital signalprocessor (DSP), a microcontroller, an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA), or the like.Also, in embodiments, the memory system 3236 may include random accessmemory (RAM), read only memory (ROM), or other electronic, optical,magnetic, or any other computer readable medium onto which is storeddata and control algorithms in a non-transitory form.

In embodiments, the cryogenic liquid reservoir 3202 can include one ormore removable/rechargeable containers or can be integrated within thecryogenic cooling system 3200. The cryogenic liquid reservoir 3202 canhave a 5000 pounds-per-square-inch (PSI) pressure rating. In theexamples of FIGS. 24 and 25, the cryogenic liquid reservoir 3202 iscoupled in fluid communication with a feeder line 3240. In someembodiments, the feeder line 3240 enables an external source to rechargethe cryogenic liquid reservoir 3202 with liquid air. In someembodiments, the aircraft 800 of FIG. 9 includes at least one cryogeniccooler system 3242 operable to generate and produce liquid air forstorage in the cryogenic liquid reservoir 3202 during operation of theat least one gas turbine engine 20 of FIG. 9. For example, the cryogeniccooler system 3242 can include one or more air cycle machines 3244operable to compress, chill, expand, pump, and condense an air flow toproduce liquid air for storage in the cryogenic liquid reservoir 3202.

As one example, the cryogenic cooler system 3242 can include a heatexchanger system 3246 operable to receive a cooling air intake 3248. Acompressor 3250 can receive bleed air 3252 from one of the gas turbineengines 20 of FIG. 9. Compressed air 3254 output by the compressor 3250can pass through the heat exchanger system 3246 to at least one turbine3256 as a cooled flow 3258 to a vacuum system 3260 and a liquid aircondensate pump system 3262 that urges liquid air through the feederline 3240 for storage in the cryogenic liquid reservoir 3202. Thecompressor 3250 and the at least one turbine 3256 may be mechanicallylinked by a coupling 3264, such as a shaft. In some embodiments, thecompressor 3250 and the at least one turbine 3256 are not physicallycoupled. The compressor 3250 can be driven mechanically by one of thegas turbine engines 20 of FIG. 9 and/or electrically using anotherelectric propulsion motor (not depicted). Although one example of thecryogenic cooler system 3242 is depicted in the examples of FIGS. 24 and25, it will be understood that additional elements and modifications arecontemplated, such as two or more turbine wheels, recirculation paths,water separation, one or more fan sections, intermediate taps, reliefvalves, and/or other such elements known in the art. Further, theworking fluid 3206 can be provided to cool other systems of the aircraft800 of FIG. 9, such as other electronic loads or gas turbine enginecomponents (not depicted).

FIG. 26 depicts a state transition diagram 3400 of the cryogenic coolingsystem 3200 of FIG. 24 and/or the cryogenic cooling system 3300 of FIG.25 in accordance with an embodiment. The cryogenic cooling system 3200,3300 can remain in an off state 3402 during a ferry mode of the aircraft800 of FIG. 9 to conserve range, fuel, and/or battery life. In the offstate 3402, the cryogenic cooler system 3242 can be disabled, forinstance, until the aircraft 800 reaches an operational state conduciveto efficient cryogenic liquid air generation, such as at cruise. In theoff state 3402, the bypass flow control valve 3218 and the main flowcontrol valve 3214 remain closed in the cryogenic cooling system 3200.In the cryogenic cooling system 3300, the main flow control valve 3214remains closed in the off state 3402. When transitioning to a low-powermode or otherwise preparing to operate the electric fan propulsion motor818 in a higher power mode of operation, the cryogenic cooling system3200, 3300 optionally and desirably transitions to a pre-cool state3404. The precooling can assist an aircraft in taxing mode by precoolingducting and the electric fan propulsion motor 818 itself such that,during an ensuing six second acceleration to takeoff power, there isreduced time lag and reduced temperature excursion to be dealt with byall surfaces that come into contact with the cryogenic fluid be itliquid or gas. For cryogenic cooling system 3200, the controller 3224can open the bypass flow control valve 3218 while the main flow controlvalve 3214 remains closed in the pre-cool state 3404. In cryogeniccooling system 3300, the controller 3224 can partially open the mainflow control valve 3214 in the pre-cool state 3404. The cryogenic coolersystem 3242 can be active during the pre-cool state 3404 to furthersupply liquid air. The purge valve 3220 can also remain closed in thepre-cool state 3404. The working fluid 3206 may be in the form of coldgaseous air (e.g., cooled to about −182 deg. C.). The propulsion motorwindings 820 and rotor 3232 may also be cooled to about −182 deg. C. inthe pre-cool state 3404.

Shortly before higher/full power is applied to the electric fanpropulsion motor 818, the cryogenic cooling system 3200, 3300transitions from the pre-cool state 3404 to a purge state 3406. Thepurge state 3406 opens the main flow control valve 3214 to increase aflow rate of the working fluid 3206 to supply a full cooling flow fromthe cryogenic liquid reservoir 3202 through the cryogenic working fluidflow control assembly 3204 to the propulsion motor windings 820. Thepurge valve 3220 is opened to vent a gaseous accumulation of the workingfluid 3206 from the cryogenic working fluid flow control assembly 3204.The purge valve 3220 can be closed after a predetermined time (e.g., inmilliseconds) and/or a detected condition (e.g., temperature and/orpressure) confirms the gas has been substantially purged. Transitioningthe purge valve 3220 from closed to opened to closed is referred to as“cycling” the purge valve 3220. Upon closing the purge valve 3220, thecryogenic cooling system 3200, 3300 transitions from the purge state3406 to the full cooling state 3408. In the full cooling state 3408, theworking fluid 3206 is delivered in a liquid state to the propulsionmotor windings 820 during operation of the electric fan aircraftpropulsion motor 818.

In some embodiments, if the power demand of the electric fan propulsionmotor 818 is reduced during operation or upon a shutdown event of theelectric fan propulsion motor 818, the cryogenic cooling system 3200,3300 can transition from the full cooling state 3408 to a reducedcooling state 3410. In embodiments where the main flow control valve3214 is a variable position valve, the position of the main flow controlvalve 3214 can be set to a partially opened state to reduce consumptionof liquid air in the reduced cooling state 3410 until a transition backto the full cooling state 3408 is needed. Further, either or both of themain flow control valve 3214 and the bypass flow control valve 3218 canbe modulated, for instance, using pulse width modulation to repeatedlyopen and close the main flow control valve 3214 and/or the bypass flowcontrol valve 3218 in the reduced cooling state 3410 to reduce a flowrate of the liquid air to the electric fan propulsion motor 818. Thereduced cooling state 3410 can be used after the electric fan propulsionmotor 818 is depowered to slowly increase the temperature of theelectric fan propulsion motor 818 and reduce thermal transient effects.The cryogenic cooling system 3200, 3300 can transition from the reducedcooling state 3410 to the off state 3402 or the full cooling state 3408.In some embodiments, the reduced cooling state 3410 is equivalent to thepre-cool state 3404. The reduced cooling state 3410 may also oralternatively supply the non-cryogenic cooling flow 3215 to thepropulsion motor windings 820 to conserve cryogenic resources and enablea lower power operation of the electric fan propulsion motor 818.

In FIG. 27 a plot 3500 depicts three possible thrust outputs from theelectric fan propulsion motor 818. The highest output level 3502, up tothe full capability of the electric fan propulsion motor 818 is wherethe full cryogenic cooling capability is presented and a 100% thrustcapability is realized. Much less thrust is available if a low flow ofcryogenic gaseous air at a reduced level 3504 is provided but theaircraft system holds the biggest part of its cryogenic resource inreserve and it is not wasted. Finally, depending on the motor design,there may be a fan integral with the electric fan propulsion motor 818or powered separately such that ambient air 817 is used for cooling andnone of the cryogenic resource is used at a lowest level 3506 with theelectric fan propulsion motor 818 at its lowest thrust.

In plot 3600 of FIG. 28, the cryogenic flows are “off” if the electricfan propulsion motor 818 is designed to pull some ambient airflow intothe motor housing for low thrust operation at a lowest level 3602.Second, the low cryogenic airflow is provided while still conserving thecryogenic resource to the greatest extent possible at level 3604, andlastly the full flow is provided for maximum propulsion motor thrust ata highest level 3606.

Turning to FIG. 29, there is a transient representation of the electriccurrent in the curve 3702 marked (a) in plot 3700, where the fullcurrent is applied in about 6 seconds, but the application of fullcurrent is not necessarily instantaneous and may be applied graduallywith as much of a time lag as is shown by the electric current ramp andlabeled by (a) since electricity is faster to course through theelectric fan propulsion motor 818 than cooling fluid can ramp up. Nextis shown two scenarios labeled mdot(slow) 3704 and mdot(fast) 3706. Inthe case of mdot(slow) 3704, the Texit temperature of the electric fanpropulsion motor 818 changes and is hotter than the other case withmdot(fast) 3706 which is the desirable circumstance in that the Texittemperature is stipulated to be acceptable for the purposes of thisexample. However, the slow introduction of cooling may not be wellcharacterized by the Texit parameter since Texit is a bulk averagetemperature and may not well represent a hottest part of the electricfan propulsion motor 818. This hottest part, called there Tlocal, may besimply an internal feature that has the most mass or is at adisadvantaged location relative to some part of cryogenic streammanifold introduction. Nevertheless, damage to the electric fanpropulsion motor 818 and the long term durability of the electric fanpropulsion motor 818 is dependent on the health of the motor componentat Tlocal. Plot 3700 shows two scenarios 3708, 3710 for Tlocal, one ofwhich is associated with mdot(slow) 3704 at scenario 3708 which locallyexceeds the maximum temperature allowed for undamaged operation and ismarked by cross hatches 3712. If however mdot (fast) 3706 is employed inembodiments, the Tlocal temperature does not exceed damage limits. It ispossible for a control standpoint to empirically and analytically relateTlocal toTexit by monitoring Texit and by correlating Tlocal to Texitand modifying the correlation by a relationship that includes the recentpast history of Texit to adjust for some amount of lag in the rate inwhich Tlocal cools from a previous power condition.

FIG. 30 is a flow chart illustrating a method 3800 of propulsion systemcooling control in accordance with an embodiment. The method 3800 ofFIG. 30 is described in reference to FIGS. 1-30 and may be performedwith an alternate order and include additional steps. The method 3800can be performed, for example, by cryogenic cooling system 3200,cryogenic cooling system 3300, or other variations.

At block 3801, a non-cryogenic cooling flow 3215 can be supplied to aplurality of propulsion motor windings 820 of an electric fan propulsionmotor 818 to provide a lower level of operability to the electric fanpropulsion motor 818. The cooling source 3219 of the non-cryogeniccooling flow 3215 can be ambient air 817 or air that is taken from anexit of an air cycle machine on board the aircraft 800 for environmentalcooling of the cabin 812.

At block 3802, a pre-cooling flow of working fluid 3206 is supplied froma cryogenic liquid reservoir 3202 through a cryogenic working fluid flowcontrol assembly 3204 to a plurality of propulsion motor windings 820 ofan electric fan propulsion motor 818. Controller 3224 can open a bypassflow control valve 3218 to provide the pre-cooling flow as a bypasscooling flow through a bypass cooling line 3216 around the main flowcontrol valve 3214. Alternatively, the controller 3224 can partiallyopen the main flow control valve 3214 to provide the pre-cooling flow.

At block 3804, a flow rate of the working fluid 3206 is increased tosupply a full cooling flow from the cryogenic liquid reservoir 3202through the cryogenic working fluid flow control assembly 3204 to thepropulsion motor windings 820. A position of the main flow control valve3214 can be modified responsive to the controller 3224 to control theflow rate of the working fluid 3206 through a primary cooling line 3208of the cryogenic working fluid flow control assembly 3204 to thepropulsion motor windings 820. For instance, the main flow control valve3214 can be commanded to fully open to increase the working fluid 3206flow rate.

Optionally, a further, low power source can be provided, as thenon-cryogenic cooling flow 3215, where a cool temperature but notcryogenic temperature source of cooling is provided so as to give theaircraft 800 the opportunity to operate the electric fan propulsionmotor 818 without using up any cryogenic resources at low power and foran unlimited time.

At block 3806, controller 3224 can cycle a purge valve 3220 of thecryogenic working fluid flow control assembly 3204 from closed to openedto closed to vent a gaseous accumulation of the working fluid 3206.

At block 3808, the working fluid 3206 is delivered in a liquid state tothe propulsion motor windings 820 during operation of the electric fanpropulsion motor 818 to increase power density with a larger electriccurrent supported during cryogenic operating conditions. A flow rate ofthe working fluid 3206 can be decreased from the full cooling flow to areduced cooling flow prior to disabling a flow of the working fluid 3206from the cryogenic liquid reservoir 3202 through the cryogenic workingfluid flow control assembly 3204 to the propulsion motor windings 820.As previously described, the reduction can be achieved by partiallyclosing the main flow control valve 3214, if supported, or modulatingeither or both of the main flow control valve 3214 and the bypass flowcontrol valve 3218 between commanding opened and closed valve positions.

On board an aircraft, there are typically multiple systems that usevarious gasses. Some types of gasses are generated on-board an aircraftand others are carried in pressurized storage containers. For example,an on-board inert gas generating system can produce nitrogen-enrichedair and supply the nitrogen-enriched air to on-board fuel storage tanksto reduce fuel vapor flammability. Oxygen gas may be stored on-board anaircraft for use by passengers and crew members in the event of cabinpressurization loss. Dedicated resources for oxygen gas storage andnitrogen generation can add to aircraft weight, complexity, and fuelconsumption.

FIG. 31 schematically illustrates a ground-based cryogenic coolingsystem 4100 including a cryogenic cooler 4102 that can be powered by apower supply 4104 through a power distribution system 4106. The powersupply 4104 can be an electric power supply from one or more renewablepower supplies of “green” power. For example, a solar array 4104A, arechargeable battery system 4104B, a wind turbine system 4104C, and/orother known types of renewable power supplies can be used to power thecryogenic cooler 4102. In the example of FIG. 31, electric currentproduced by the solar array 4104A and/or the wind turbine system 4104Ccan be stored in the rechargeable battery system 4104B when thecryogenic cooler 4102 is not operating, or the cryogenic cooler 4102 isactively drawing less current than is produced by the solar array 4104Aand/or the wind turbine system 4104C. Alternatively, the system can beused to absorb the extra capacity of a nuclear power, hydro or windplant in times when less than peak loads are being serviced by theenergy grid in order to reduce the emission of carbon into theatmosphere during high electric grid use.

The cryogenic cooler 4102 is an example of a means for cooling anairflow to produce chilled air. The cryogenic cooler 4102 can include aheat exchanger system 4146 operable to receive a cooling air intake 4148that can be drawn by a fan (not depicted). A compressor 4150 can receivean airflow 4152, for instance, from a fan (not depicted) and producecompressed air 4154. An electric motor 4110 is operable to driverotation of the compressor 4150 responsive to electric current from thepower supply 4104. Compressed air 4154 that is output by the compressor4150 can pass through the heat exchanger system 4146 and through a waterseparator 4112 to produce dried cool air 4155. The water separator 4112is a means for separating water vapor using a condenser, such as acyclonic separator or similar structure that can swirl air over animpingement surface to cause moisture condensation, for instance, usingcentrifugal force. Water 4114 extracted at the water separator 4112 canbe discarded or may be sprayed proximate to an intake of the heatexchanger system 4146 to further cool the cooling air intake 4148. Aturbine assembly 4156 can include one or more turbines in fluidcommunication with the water separator 4112, where the turbine assembly4156 is configured to expand the dried cool air 4155 and produce chilledair 4158. The chilled air 4158 can pass through a vacuum system 4160 anda liquid air condensate pump system 4162 that condenses the chilled air4158 into liquid air 4164 and urges the liquid air 4164 through a feederline 4140 for storage in a cryogenic liquid reservoir 4122 of acryogenic cartridge 4120.

The cryogenic cartridge 4120 includes a coupling interface 4124configured to detachably establish fluid communication with the feederline 4140, and the cryogenic liquid reservoir 4122 is configured tostore the liquid air 4164 under pressure. As one example, the cryogenicliquid reservoir 4122 can have a 5000 pounds-per-square-inch (PSI)pressure rating. The cryogenic cartridge 4120 can also include a rapidrelease component 4126 operable to depressurize the cryogenic liquidreservoir 4122 upon impact. For example, the rapid release component4126 can include a venting system or a blow-out panel configured torelease contents of the cryogenic liquid reservoir 4122 upon asubstantial impact to the cryogenic cartridge 4120, such as a crashevent.

In some embodiments, the electric motor 4110 can drive the compressor4150 through a gearbox 4130 that drives a shaft 4132 coupled to thecompressor 4150. Rotation of the turbine assembly 4156 may drive a shaft4134 that provides another input to the gearbox 4130. In alternateembodiments, there is no mechanical coupling between the compressor 4150and the turbine assembly 4156. For example, the electric motor 4110 candirectly drive the shaft 4132 and work output on the shaft 4134 candrive rotation of another element (not depicted).

Although one example of the cryogenic cooler 4102 is depicted in theexample of FIG. 31, it will be understood that additional elements andmodifications are contemplated, such as two or more turbine wheels,recirculation paths, one or more fan sections, intermediate taps, reliefvalves, and/or other such elements known in the art. For instance, thechilled air 4158 may be recirculated through the cryogenic cooler 4102to progressively reduce the temperature to cryogenic temperatures tosupport liquefaction of air. Further, the cryogenic cooler 4102 maysupport filling of multiple cryogenic cartridges 4120 as depicted in theexample of FIG. 32.

FIG. 32 is a schematic illustration of a filling station 4200 operableto pressurize and store the liquid air 4164 of FIG. 31 in a plurality ofcryogenic cartridges 4120A, 4120B, 4120C, 4120D. For example, when thecryogenic cooler 4102 is actively producing liquid air 4164, multiplecryogenic cartridges 4120A-4120D can be filled in parallel. Thecryogenic cartridges 4120A-4120D can be detached for transport/use asneeded. As cryogenic cartridges 4120A-4120D are emptied and returned,the cryogenic cartridges 4120A-4120D can be refilled at the fillingstation 4200, which may be an extension of the feeder line 4140 of FIG.31. In some embodiments, a pressure monitoring system and/or weightmonitoring system can be used determine the fill state of the cryogeniccartridges 4120A-4120D. In an embodiment, when conditions are favorablefor electric current output by one or more of power supply 4104, such asa sunny day or a windy day, any of the cryogenic cartridges 4120A-4120Ddocked at the filling station 4200 can be at least partially rechargedwith liquid air 4164 as needed. Although the example of FIG. 32 depictsfour cryogenic cartridges 4120A-4120D at the filling station 4200, anynumber of cryogenic cartridges 4120 can be supported depending upondesign constraints.

FIG. 33 is a schematic illustration of a cryogenic system 4300 for anaircraft 4302. The cryogenic system 4300 includes a cryogenic liquiddistribution system 4304 with one or more cryogenic fluid flow paths4306. The coupling interface 4124 of the cryogenic cartridge 4120 ofFIG. 31 can be attached to the cryogenic liquid distribution system 4304to establish fluid communication with the cryogenic liquid distributionsystem 4304. Once the cryogenic liquid reservoir 4122 configured tostore liquid air under pressure as a cryogenic working fluid 4314 issubstantially depleted, the coupling interface 4124 can be used todetach the cryogenic cartridge 4120 and reattach one of the cryogeniccartridges 4120A-4120D of FIG. 32 that has previously been filled. Insome embodiments, the cryogenic liquid reservoir 4122 can be at leastpartially refilled while coupled to the cryogenic liquid distributionsystem 4304 using an on-board cryogenic cooler 4308, if available,and/or a filling port 4310. When available on the aircraft 4302, theon-board cryogenic cooler 4308 is operable to at least partiallyrecharge the cryogenic cartridge 4120 during aircraft operation, forinstance, while operating in a cruise or descent flight phase. Thecryogenic cartridge 4120 can be positioned within the aircraft 4302 at aserviceable location that enables attachment and detachment of thecryogenic cartridge 4120 by a ground service crew during routine groundservicing operations, e.g., fueling the aircraft 4302. The cryogeniccartridge 4120 may be positioned such that liquid air discharged by therapid release component 4126 during an impact event reduces the risk ofan adverse result to other components and/or a cabin area of theaircraft 4302.

One or more cryogenic usage systems 4312 can be in fluid communicationwith the one or more cryogenic fluid flow paths 4306 and configured toselectively receive a cryogenic working fluid 4314 discharged throughthe coupling interface 4124 of the cryogenic cartridge 4120. Dependingupon the temperature and placement of the cryogenic usage systems 4312,the cryogenic working fluid 4314 may initially be received as coolingair or a mixture of liquid air and cooling air. Examples of thecryogenic usage systems 4312 include an electric motor cryogenic coolingsystem 4320, a gas turbine engine cooling system 4322, and a powerelectronics cooling system 4324. The electric motor cryogenic coolingsystem 4320, gas turbine engine cooling system 4322, and powerelectronics cooling system 4324 can include a combination of plumbinglines and control valves to target particular components and systemswith a cooling fluid flow. The cryogenic working fluid 4314 mayalternatively or additionally be selectively provided to a gasseparation system 4326. The gas separation system 4326 may receive thecryogenic working fluid 4314 as liquid air and produce gaseous nitrogen4328 and liquid oxygen 4330, for example. The gaseous nitrogen 4328 canbe provided to a fuel tank inerting system 4332 as a main supply orsupplement to an on-board inert gas generation system, for instance, toreduce fuel vapor flammability. The liquid oxygen 4330 may be providedto either or both of a breathable oxygen system 4334 and a combustionenhancement system 4336. Liquid oxygen 4330 can supplement or be aprimary source of breathable oxygen after conditioning (e.g.,temperature and pressure control) for the aircraft 4302. Liquid oxygen4330 may also or alternatively be used by a combustion enhancementsystem 4336 to provide oxygen-enriched air to a compressor section of agas turbine engine of the aircraft 4302 prior to combustion. Other useson the aircraft 4302 are contemplated. Although multiple cryogenic usagesystems 4312 are depicted as aircraft uses in FIG. 33, it will beunderstood that a subset (one or more) of the cryogenic usage systems4312 may be implemented on the aircraft 4302. Further, the cryogenicusage systems 4312 may have separate instances of the cryogeniccartridge 4120 positioned in closer physical proximity if needed.Several examples of the cryogenic usage systems 4312 are depicted in theFIGS. 34-37 as further described herein.

FIG. 34 depicts an electric motor cryogenic cooling system 4400 as anexample of the electric motor cryogenic cooling system 4320 of FIG. 33according to an embodiment. The electric motor cryogenic cooling system4400 includes one or more cryogenic cartridge 4120 and a cryogenicworking fluid flow control assembly 4404 in fluid communication withmotor windings 4450 of the electric fan motor 4458. A cryogenic fluidcoupling 4402 can provide an access port for transferring cryogenicworking fluid 4314 to or refilling the cryogenic cartridge 4120, forinstance, from cryogenic fluid flow paths 4306 and/or a filling port4310 of FIG. 33. The electric motor cryogenic cooling system 4400 isoperable to control a flow rate of a cryogenic working fluid 4314through the cryogenic working fluid flow control assembly 4404 to themotor windings 4450. The cryogenic working fluid 4314 can be liquid airreleased from the cryogenic liquid reservoir 4122, cool gaseous air,and/or a mix of liquid and gaseous air. For example, the liquid air canbe stored under pressure in the cryogenic liquid reservoir 4122 and maychange to a gaseous state upon entering a warmer environment of thecryogenic working fluid flow control assembly 4404. As the cryogenicworking fluid flow control assembly 4404 is cooled, the cryogenicworking fluid 4314 may pass through a primary cooling line 4408 andreach a manifold 4410 of the cryogenic working fluid flow controlassembly 4404 as liquid air to cryogenically chill the motor windings4450. The manifold 4410 can include multiple taps 4412 to flow thecryogenic working fluid 4314 into close proximity with the motorwindings 4450.

A combination of valves can be used to control the flow rate of thecryogenic working fluid 4314. For example, a main flow control valve4414 is operable to control the flow rate of the cryogenic working fluid4314 through a primary cooling line 4408 of the cryogenic working fluidflow control assembly 4404 to the motor windings 4450. In someembodiments, the main flow control valve 4414 is a variable positionvalve operable to transition between a closed position, a partiallyopened position to supply a pre-cooling flow, and a fully openedposition to supply a full cooling flow. The terms “full” and “fully”refer to a sufficient level to meet a demand and need not be the maximumlevel attainable. In other embodiments, the main flow control valve 4414is a discrete on/off valve that can be commanded to either a fullyopened or a fully closed position. The cryogenic working fluid flowcontrol assembly 4404 can also include a bypass cooling line 4416 and abypass flow control valve 4418 configured to selectively provide apre-cooling flow as a bypass cooling flow around the main flow controlvalve 4414. The electric motor cryogenic cooling system 4400 of FIG. 34is an example of a system that includes the bypass cooling line 4416 andbypass flow control valve 4418.

With continued reference to FIG. 34, a purge valve 4420 can be coupledto the manifold 4410 proximate to a housing 4422 of the electric fanmotor 4458. The purge valve 4420 can be controlled to release gaseousair that has accumulated in the cryogenic working fluid flow controlassembly 4404 as part of a process of supplying a pre-cooling flow ofthe cryogenic working fluid 4314 from the cryogenic liquid reservoir4122 through the cryogenic working fluid flow control assembly 4404 tothe motor windings 4450.

A controller 4424 can interface with the main flow control valve 4414,the bypass flow control valve 4418, and the purge valve 4420 through aninput/output interface 4426. The controller 4424 can also interface withone or more sensors, such as one or more temperature sensors 4428 and/orone or more pressure sensors 4430. Temperature sensors 4428 can belocated proximate to the purge valve 4420, proximate to one or more taps4412 of the manifold 4410, and/or at other locations to determine atemperature within the manifold 4410, an exit temperature, or othertemperatures. Although depicted proximate to the housing 4422 andmanifold 4410, the pressure sensors 4430 can be located remotely fromthe housing 4422 and manifold 4410 if pressure taps and ducting areused. The controller 4424 can be combined with one or more othercontrollers (not depicted) of the aircraft 4302 of FIG. 33.

In embodiments, the controller 4424 is operable to control changes inthe flow rate of the cryogenic working fluid 4314 and timing of openingand closing the purge valve 4420 based on temperature data from the oneor more temperature sensors 4428. The controller 4424 may alternativelyor additionally be operable to control changes in the flow rate of thecryogenic working fluid 4314 and timing of opening and closing the purgevalve 4420 based on pressure data from the one or more pressure sensors4430. In some embodiments, a speed of rotation of a rotor 4432 of theelectric fan motor 4458 is limited responsive to confirming whether thecryogenic working fluid 4314 is reaching the motor windings 4450 in aliquid state. Temperature and/or pressure data from the temperaturesensors 4428 and pressure sensors 4430 can be used to confirm whetherthe cryogenic working fluid 4314 is in a liquid state or that sufficientcooling is reaching a temperature-limited internal component based on ananalytical and empirically verified correlation between the measuredexit temperature and the electric current being input to the electricfan motor 4458 and therefrom estimating the temperature of thecomponent. A motor controller (not depicted) can set or limit theelectric current provided to the motor windings 4450 based ondetermining whether the cryogenic working fluid 4314 is in the liquidstate at the motor windings 4450. A communication interface 4434 of thecontroller 4424 can send a limit signal, a liquid state confirmationsignal, and/or other signals to control the electric fan motor 4458.

In an embodiment, the controller 4424 also includes a memory system 4436to store instructions that are executed by a processing system 4438 ofthe controller 4424. The executable instructions may be stored ororganized in any manner and at any level of abstraction, such as inconnection with a controlling and/or monitoring operation of theelectric motor cryogenic cooling system 4400. The processing system 4438can include one or more processors that can be any type of centralprocessing unit (CPU), including a microprocessor, a digital signalprocessor (DSP), a microcontroller, an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA), or the like.Also, in embodiments, the memory system 4436 may include random accessmemory (RAM), read only memory (ROM), or other electronic, optical,magnetic, or any other computer readable medium onto which is storeddata and control algorithms in a non-transitory form.

The cryogenic cartridge 4120 is detachably coupled by the couplinginterface 4124 in fluid communication with a feeder line 4440. In someembodiments, the feeder line 4440 enables another source to recharge thecryogenic liquid reservoir 4122 with liquid air through the cryogenicfluid coupling 4402, for instance, from the on-board cryogenic cooler4308 of FIG. 33.

FIG. 35 depicts a schematic illustration of an on-board cryogenic cooler4500 as an example of the on-board cryogenic cooler 4308 of FIG. 33 inaccordance with an embodiment. The cryogenic cooler 4500 can include oneor more air cycle machines 4544 operable to compress, chill, expand,pump, and condense an air flow to produce liquid air for storage in thecryogenic liquid reservoir 4122 and/or immediate use. As one example,the cryogenic cooler 4500 can include a heat exchanger system 4546operable to receive a cooling air intake 4548. A compressor 4550 canreceive bleed air 4552 from a gas turbine engine (not depicted) as anair flow. Compressed air 4554 output by the compressor 4550 can passthrough the heat exchanger system 4546 to at least one turbine 4556 as acooled flow 4558 to a vacuum system 4560 and a liquid air condensatepump system 4562 that urges liquid air through into the cryogenic liquiddistribution system 4304 of FIG. 33. The compressor 4550 and the atleast one turbine 4556 may be mechanically linked by a coupling 4564,such as a shaft. In some embodiments, the compressor 4250 and the atleast one turbine 4556 are not physically coupled. The compressor 4550can be driven mechanically by a gas turbine engine and/or electricallyusing an electric motor (not depicted). Although one example of thecryogenic cooler 4500 is depicted in the example of FIG. 35, it will beunderstood that additional elements and modifications are contemplated,such as two or more turbine wheels, recirculation paths, waterseparation, one or more fan sections, intermediate taps, relief valves,and/or other such elements known in the art.

FIG. 36 depicts a schematic illustration of a cryogenic air separator4600 as an example of the gas separation system 4326 of FIG. 33 inaccordance with an embodiment. The cryogenic air separator 4600 caninclude a separation vessel 4602 with at least one liquid air input port4604, at least one gaseous nitrogen output port 4606, and at least oneliquid oxygen output port 4608. The liquid air input port 4604 isoperable to receive a liquid air flow from the cryogenic working fluid4314 of FIG. 33. The temperature of the liquid air flow can be below theboiling points of nitrogen, oxygen, and other constituents of air uponreaching liquid air input port 4604. The separation vessel 4602 can besized, located, and otherwise temperature controlled to allow nitrogento boil off from the liquid air flow through the gaseous nitrogen outputport 4606 as gaseous nitrogen 4328 while liquid oxygen 4330 remains andflows out of the liquid oxygen output port 4608. For instance, inreference to an example at ambient atmospheric pressure, as the liquidair flow is warmed from about −200 degrees C., nitrogen would boil offat temperatures at or above −195.8 degrees C., leaving liquid oxygen oran oxygen-rich liquid if the temperature remains below −183 degrees C.,for example. The separation in the cryogenic air separator 4600 can betemperature-based in that differences in boiling points of nitrogen andoxygen allow for nitrogen to transition into a gaseous state whileoxygen (and potentially argon) remains liquefied while the temperatureof the cryogenic working fluid 4314 rises upon entry into the separationvessel 4602. The pressure of the cryogenic working fluid 4314 can beset/adjusted to match the separation performance properties of thecryogenic air separator 4600, as liquid/gas state is a function ofpressure and temperature. Although the example of FIG. 36 includes asingle separation vessel 4602, it will be understood that otherconfigurations can be implemented, such as a series of separationvessels 4602, along with other features to further enhance separationperformance.

FIG. 37 is a flow chart illustrating a method 4700 of ground-basedfilling of a cryogenic cartridge 4120 for an aircraft use (e.g.,aircraft 4302 of FIG. 33) in accordance with an embodiment. The method4700 of FIG. 37 is described in reference to FIGS. 1-37 and may beperformed with an alternate order and include additional steps. Themethod 4700 can be performed, for example, by the ground-based cryogeniccooling system 4100, the cryogenic system 4300, and/or other variations.

At block 4702, a ground-based cryogenic cooling system 4100 is operatedto produce a volume of liquid air 4164. The compressor 4150 of thecryogenic cooler 4102 can produce compressed air 4154 responsive torotation driven by an electric motor 4110. The compressed air 4154 canbe cooled through a heat exchanger system 4146. Water 4114 can beremoved from cooled compressed air 4154 to produce dried cool air 4155.The dried cool air 4155 can be expanded through a turbine assembly 4156to produce chilled air 4158. Condensing of the chilled air 4158 into theliquid air 4164 can be performed using the liquid air condensate pumpsystem 4162. The electric motor 4110 can be powered by a renewable powersource including one or more of: a solar array 4104A, a wind turbinesystem 4104C, and a rechargeable battery system 4104B.

At block 4704, the liquid air 4164 is pressurized and stored in acryogenic cartridge 4120. The liquid air 4164 can be urged through afeeder line 4140 into the cryogenic cartridge 4120. As previouslydescribed, the cryogenic cartridge 4120 can include a coupling interface4124 configured to detachably establish fluid communication with thefeeder line 4140 and a cryogenic liquid reservoir 4122 configured tostore the liquid air 4164 under pressure. The cryogenic cartridge 4120can also include a rapid release component 4126 operable to depressurizethe cryogenic liquid reservoir 4122 upon impact.

At block 4706, the cryogenic cartridge 4120 is coupled to a cryogenicliquid distribution system 4304 on an aircraft 4302. At block 4708,liquid air is selectively released from the cryogenic cartridge 4120 asa cryogenic working fluid 4314 through the cryogenic liquid distributionsystem 4304 for an aircraft use. The aircraft use can include one ormore cryogenic usage systems 4312, such as one or more of: cryogenicallycooling an electric motor using an electric motor cryogenic coolingsystem 4320, cooling one or more components of a gas turbine engineusing a gas turbine engine cooling system 4322, and/or cooling powerelectronics of the aircraft 4302 using a power electronics coolingsystem 4324. In some embodiments, liquid air is passed through a gasseparation system 4326 to produce gaseous nitrogen 4328 and liquidoxygen 4330 for various aircraft uses, such as providing the gaseousnitrogen 4328 to a fuel tank inerting system 4332 and providing theliquid oxygen 4330 to either or both of a breathable oxygen system 4334and a combustion enhancement system 4336. Further, an on-board cryogeniccooler 4308 can be controlled to at least partially recharge thecryogenic cartridge 4120 during aircraft operation.

The term “about” is intended to include the degree of error associatedwith measurement of the particular quantity based upon the equipmentavailable at the time of filing the application.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentdisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,element components, and/or groups thereof.

While the present disclosure has been described with reference to anexemplary embodiment or embodiments, it will be understood by thoseskilled in the art that various changes may be made and equivalents maybe substituted for elements thereof without departing from the scope ofthe present disclosure. In addition, many modifications may be made toadapt a particular situation or material to the teachings of the presentdisclosure without departing from the essential scope thereof.Therefore, it is intended that the present disclosure not be limited tothe particular embodiment disclosed as the best mode contemplated forcarrying out this present disclosure, but that the present disclosurewill include all embodiments falling within the scope of the claims.

What is claimed is:
 1. A propulsion system comprising: an electric fanpropulsion motor comprising a plurality of propulsion motor windings;and a means for controlling a flow rate of a working fluid through acryogenic working fluid flow control assembly to the propulsion motorwindings.
 2. The propulsion system of claim 1, wherein the cryogenicworking fluid flow control assembly comprises a manifold and a purgevalve proximate to a housing of the electric fan propulsion motor. 3.The propulsion system of claim 2, wherein the means for cryogeniccooling comprises a cryogenic liquid reservoir and a controller operableto: supply a pre-cooling flow of the working fluid from the cryogenicliquid reservoir through the cryogenic working fluid flow controlassembly to the propulsion motor windings; increase a flow rate of theworking fluid to supply a full cooling flow from the cryogenic liquidreservoir through the cryogenic working fluid flow control assembly tothe propulsion motor windings; cycle the purge valve to vent a gaseousaccumulation of the working fluid; and deliver the working fluid in aliquid state to the propulsion motor windings during operation of theelectric fan propulsion motor.
 4. The propulsion system of claim 3,wherein the cryogenic working fluid flow control assembly comprises amain flow control valve operable to control the flow rate of the workingfluid through a primary cooling line of the cryogenic working fluid flowcontrol assembly to the propulsion motor windings.
 5. The propulsionsystem of claim 4, wherein the main flow control valve is a variableposition valve operable to transition between a closed position, apartially opened position to supply the pre-cooling flow, and a fullyopened position to supply the full cooling flow.
 6. The propulsionsystem of claim 4, wherein the cryogenic working fluid flow controlassembly comprises a bypass cooling line and a bypass flow control valveconfigured to selectively provide the pre-cooling flow as a bypasscooling flow around the main flow control valve.
 7. The propulsionsystem of claim 3, further comprising one or more temperature sensors,wherein the controller is operable to control changes in the flow rateof the working fluid and timing of opening and closing the purge valvebased on temperature data from the one or more temperature sensors. 8.The propulsion system of claim 3, further comprising one or morepressure sensors, wherein the controller is operable to control changesin the flow rate of the working fluid and timing of opening and closingthe purge valve based on pressure data from the one or more pressuresensors.
 9. The propulsion system of claim 3, wherein a speed of theelectric fan propulsion motor is limited responsive to confirmingwhether the working fluid is reaching the propulsion motor windings inthe liquid state.
 10. The propulsion system of claim 3, wherein thecontroller is operable to decrease a flow rate of the working fluid fromthe full cooling flow to a reduced cooling flow prior to disabling aflow of the working fluid from the cryogenic liquid reservoir throughthe cryogenic working fluid flow control assembly to the propulsionmotor windings.
 11. A method comprising: operating a ground-basedcryogenic cooling system to produce a volume of liquid air; pressurizingand storing the liquid air in a cryogenic cartridge; coupling thecryogenic cartridge to a cryogenic liquid distribution system on anaircraft; and selectively releasing the liquid air from the cryogeniccartridge through the cryogenic liquid distribution system for anaircraft use.
 12. The method of claim 11, further comprising: producingcompressed air by a compressor responsive to rotation driven by anelectric motor; cooling the compressed air through a heat exchangersystem; removing water from the cooled compressed air to produce driedcool air; and expanding the dried cool air through a turbine assembly toproduce chilled air.
 13. The method of claim 12, further comprising:condensing the chilled air into the liquid air; and urging the liquidair through a feeder line into the cryogenic cartridge.
 14. The methodof claim 3, wherein the cryogenic cartridge comprises a couplinginterface configured to detachably establish fluid communication withthe feeder line and a cryogenic liquid reservoir configured to store theliquid air under pressure.
 15. The method of claim 14, wherein thecryogenic cartridge comprises a rapid release component operable todepressurize the cryogenic liquid reservoir upon impact.
 16. The methodof claim 12, wherein the electric motor is powered by a renewable powersource comprising one or more of: a solar array, a wind turbine system,and a rechargeable battery system.
 17. The method of claim 11, whereinthe aircraft use comprises cryogenically cooling an electric motor. 18.The method of claim 11, wherein the aircraft use comprises cooling oneor more components of a gas turbine engine.
 19. The method of claim 11,wherein the aircraft use comprises cooling power electronics of theaircraft.
 20. The method of claim 11, further comprising: passing theliquid air through a gas separation system to produce gaseous nitrogenand liquid oxygen; providing the gaseous nitrogen to a fuel tankinerting system; and providing the liquid oxygen to either or both of abreathable oxygen system and a combustion enhancement system.